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Flowering plants are
plants Plants are predominantly Photosynthesis, photosynthetic eukaryotes of the Kingdom (biology), kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all curr ...
that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the
Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...
words ('container, vessel') and ('seed'), and refers to those plants that produce their
seeds A seed is an Plant embryogenesis, embryonic plant enclosed in a testa (botany), protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, includ ...
enclosed within a
fruit In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering. Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in particul ...
. They are by far the most diverse group of
land plants The Embryophyta (), or land plants, are the most familiar group of green plants that comprise vegetation on Earth. Embryophytes () have a common ancestor with green algae, having emerged within the Phragmoplastophyta clade of green algae as siste ...
with 64 orders, 416
families Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...
, approximately 13,000 known
genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
and 300,000 known
species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...
. Angiosperms were formerly called Magnoliophyta (). Like
gymnosperm The gymnosperms ( lit. revealed seeds) are a group of seed-producing plants that includes conifers, cycads, '' Ginkgo'', and gnetophytes, forming the clade Gymnospermae. The term ''gymnosperm'' comes from the composite word in el, γυμν ...
s, angiosperms are seed-producing plants. They are distinguished from gymnosperms by characteristics including
flower A flower, sometimes known as a bloom or blossom, is the reproduction, reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providin ...
s,
endosperm The endosperm is a tissue produced inside the seeds of most of the flowering plants following double fertilization. It is triploid (meaning three chromosome sets per nucleus) in most species, which may be auxin-driven. It surrounds the Embryo#Plant ...
within their seeds, and the production of fruits that contain the seeds. The ancestors of flowering plants diverged from the common ancestor of all living gymnosperms before the end of the
Carboniferous The Carboniferous ( ) is a Period (geology), geologic period and System (stratigraphy), system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago (Myr, Mya), to the beginning of the Permian Period, ...
, over 300 million years ago. The closest fossil relatives of flowering plants are uncertain and contentious. The earliest angiosperm fossils are in the form of pollen around 134 million years ago during the
Early Cretaceous The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145& ...
. Over the course of the
Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 79 million years, it is the long ...
, angiosperms explosively diversified, becoming the dominant group of plants across the planet by the end of the period, corresponding with the decline and extinction of previously widespread gymnosperm groups. The origin and diversification of the angiosperms is often known as "Darwin's abominable mystery".


Description


Angiosperm derived characteristics

Angiosperms differ from other seed plants in several ways, described in the table below. These distinguishing characteristics taken together have made the angiosperms the most diverse and numerous land plants, and the most commercially important group to humans.


Vascular anatomy

Angiosperm stems are made up of seven layers as shown on the right. The amount and
complexity Complexity characterises the behaviour of a system or model whose components interaction, interact in multiple ways and follow local rules, leading to nonlinearity, randomness, collective dynamics, hierarchy, and emergence. The term is generall ...
of tissue-formation in flowering plants exceeds that of gymnosperms. In the
dicotyledon The dicotyledons, also known as dicots (or, more rarely, dicotyls), are one of the two groups into which all the flowering plants (angiosperms) were formerly divided. The name refers to one of the typical characteristics of the group: namely, t ...
s, the
vascular bundle A vascular bundle is a part of the transport system in vascular plants. The transport itself happens in the Plant stem, stem, which exists in two forms: xylem and phloem. Both these tissues are present in a vascular bundle, which in addition ...
s of the stem are arranged such that the
xylem Xylem is one of the two types of transport tissue in vascular plant Vascular plants (), also called tracheophytes () or collectively Tracheophyta (), form a large group of embryophyte, land plants ( accepted known species) that have lignin, ...
and
phloem Phloem (, ) is the living biological tissue, tissue in vascular plants that transports the soluble organic compounds made during photosynthesis and known as ''photosynthates'', in particular the sugar sucrose, to the rest of the plant. This tran ...
form concentric rings. The bundles in the very young stem are arranged in an open ring, separating a central pith from an outer cortex. In each bundle, separating the xylem and phloem, is a layer of
meristem The meristem is a type of biological tissue, tissue found in plants. It consists of undifferentiated cells (meristematic cells) capable of mitosis, cell division. Cells in the meristem can develop into all the other tissues and organs that occur i ...
or active formative tissue known as
cambium A cambium (plural cambia or cambiums), in plants, is a tissue layer that provides partially undifferentiated plant cell, cells for plant growth. It is found in the area between xylem and phloem. A cambium can also be defined as a cellular plant t ...
. By the formation of a layer of
cambium A cambium (plural cambia or cambiums), in plants, is a tissue layer that provides partially undifferentiated plant cell, cells for plant growth. It is found in the area between xylem and phloem. A cambium can also be defined as a cellular plant t ...
between the bundles (interfascicular cambium), a complete ring is formed, and a regular periodical increase in thickness results from the development of xylem on the inside and phloem on the outside. The soft phloem becomes crushed, but the hard wood persists and forms the bulk of the stem and branches of the woody perennial. Owing to differences in the character of the elements produced at the beginning and end of the season, the wood is marked out in transverse section into concentric rings, one for each
season A season is a division of the year based on changes in weather, ecology, and the number of daylight hours in a given region. On Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While ...
of growth, called
annual rings Dendrochronology (or tree-ring dating) is the scientific method of chronological dating, dating tree rings (also called growth rings) to the exact year they were formed. As well as dating them, this can give data for dendroclimatology, the stud ...
. Among the
monocotyledon Monocotyledons (), commonly referred to as monocots, (Lilianae ''sensu'' Chase & Reveal) are grass and grass-like flowering plants (angiosperms), the seeds of which typically contain only one Embryo#Plant embryos, embryonic leaf, or cotyledon. Th ...
s, the bundles are more numerous in the young stem and are scattered through the ground tissue. They contain no cambium and once formed the stem increases in diameter only in exceptional cases.


Reproductive anatomy

The characteristic feature of angiosperms is the flower. Flowers show remarkable variation in form and elaboration, and provide the most trustworthy external characteristics for establishing relationships among angiosperm species. The function of the flower is to ensure
fertilization Fertilisation or fertilization (see American and British English spelling differences#-ise, -ize (-isation, -ization), spelling differences), also known as generative fertilisation, syngamy and impregnation, is the fusion of gametes to give ...
of the
ovule In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: the ''integument'', forming its outer layer, the ''nucellus'' (or remnant of the sporangium, megasporangium), ...
and development of
fruit In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering. Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in particul ...
containing
seed A seed is an Plant embryogenesis, embryonic plant enclosed in a testa (botany), protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, includ ...
s. The floral apparatus may arise terminally on a shoot or from the
axil A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...
of a leaf (where the petiole attaches to the stem). Occasionally, as in violets, a flower arises singly in the axil of an ordinary foliage-leaf. More typically, the flower-bearing portion of the plant is sharply distinguished from the foliage-bearing or vegetative portion, and forms a more or less elaborate branch-system called an
inflorescence An inflorescence is a group or cluster of flower A flower, sometimes known as a bloom or blossom, is the reproduction, reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a fl ...
. There are two kinds of reproductive cells produced by flowers.
Microspore Microspores are land plant spores that develop into male gametophytes, whereas megaspores develop into female gametophytes. The male gametophyte gives rise to sperm cells, which are used for fertilization of an egg cell to form a zygote. Megaspor ...
s, which will divide to become
pollen grains Pollen is a powdery substance produced by Spermatophyte, seed plants. It consists of pollen grains (highly reduced microgametophytes), which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects ...
, are the "male" cells and are borne in the
stamen The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filame ...
s (or microsporophylls). The "female" cells called
megaspore Megaspores, also called macrospores, are a type of spore that is present in heterosporous plants. These plants have two spore types, megaspores and microspores. Generally speaking, the megaspore, or large spore, germinates into a female gametophy ...
s, which will divide to become the egg cell ( megagametogenesis), are contained in the
ovule In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: the ''integument'', forming its outer layer, the ''nucellus'' (or remnant of the sporangium, megasporangium), ...
and enclosed in the
carpel Gynoecium (; ) is most commonly used as a collective term for the parts of a flower that produce ovules and ultimately develop into the fruit and seeds. The gynoecium is the innermost whorl (botany), whorl of a flower; it consists of (one or m ...
(or megasporophyll). The flower may consist only of these parts, as in
willow Willows, also called sallows and osiers, from the genus ''Salix'', comprise List of Salix species, around 400 speciesMabberley, D.J. 1997. The Plant Book, Cambridge University Press #2: Cambridge. of typically deciduous trees and shrubs, found ...
, where each flower comprises only a few
stamen The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filame ...
s or two carpels. Usually, other structures are present and serve to protect the
sporophyll A sporophyll is a leaf that bears sporangia. Both microphylls and megaphylls can be sporophylls. In heterosporous plants, sporophylls (whether they are microphylls or megaphylls) bear either megasporangia and thus are called megasporophylls, or mi ...
s and to form an envelope attractive to pollinators. The individual members of these surrounding structures are known as
sepal A sepal () is a part of the flower A flower, sometimes known as a bloom or blossom, is the reproduction, reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to ...
s and
petal Petals are modified Leaf, leaves that surround the reproductive parts of flowers. They are often advertising coloration, brightly colored or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''c ...
s (or
tepal A tepal is one of the outer parts of a flower (collectively the perianth). The term is used when these parts cannot easily be classified as either sepals or petals. This may be because the parts of the perianth are undifferentiated (i.e. of very ...
s in flowers such as ''
Magnolia ''Magnolia'' is a large genus of about 210 to 340The number of species in the genus ''Magnolia'' depends on the taxonomic view that one takes up. Recent molecular and morphology (biology), morphological research shows that former genera ''Talaum ...
'' where sepals and petals are not distinguishable from each other). The outer series (calyx of sepals) is usually green and leaf-like, and functions to protect the rest of the flower, especially the bud. The inner series (corolla of petals) is, in general, white or brightly colored, and is more delicate in structure. It functions to attract
insect Insects (from Latin ') are pancrustacean Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, Thorax (ins ...
or
bird Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...
pollinators. Attraction is effected by color,
scent An odor (American English) or odour (English in the Commonwealth of Nations, Commonwealth English; American and British English spelling differences#-our, -or, see spelling differences) is caused by one or more volatilized chemical compounds ...
, and
nectar Nectar is a sugar-rich liquid produced by plants in glands called nectaries or nectarines, either within the flowers with which it attracts pollination, pollinating animals, or by extrafloral nectaries, which provide a nutrient source to anim ...
, which may be secreted in some part of the flower. The characteristics that attract pollinators account for the popularity of flowers and flowering plants among humans. While the majority of flowers are perfect or
hermaphrodite In reproductive biology, a hermaphrodite () is an organism that has both kinds of reproductive organs and can produce both gametes associated with male and female sexes. Many Taxonomy (biology), taxonomic groups of animals (mostly invertebrate ...
(having both pollen and ovule producing parts in the same flower structure), flowering plants have developed numerous morphological and
physiological Physiology (; ) is the science, scientific study of function (biology), functions and mechanism (biology), mechanisms in a life, living system. As a branches of science, sub-discipline of biology, physiology focuses on how organisms, organ syst ...
mechanisms to reduce or prevent self-fertilization. Heteromorphic flowers have short carpels and long stamens, or vice versa, so animal
pollinator A pollinator is an animal that moves pollen from the male anther of a flower to the female carpel, stigma of a flower. This helps to bring about fertilization of the ovules in the flower by the male gametes from the pollen grains. Insects are ...
s cannot easily transfer pollen to the pistil (receptive part of the carpel). Homomorphic flowers may employ a biochemical (physiological) mechanism called
self-incompatibility Self-incompatibility (SI) is a general name for several genetic mechanisms that prevent self-fertilization in sexually reproducing organisms, and thus encourage outcross Out-crossing or out-breeding is the technique of crossing between differ ...
to discriminate between self and non-self pollen grains. Alternatively, in
dioecious Dioecy (; ; adj. dioecious , ) is a characteristic of a species, meaning that it has distinct individual organisms (unisexual) that produce male or female gametes, either directly (in animals) or indirectly (in Spermatophyte, seed plants). Dioeci ...
species, the male and female parts are morphologically separated, developing on different individual flowers.


Taxonomy


History of classification

The botanical term "angiosperm", from Greek words ( 'bottle, vessel') and ( 'seed'), was coined in the form "Angiospermae" by Paul Hermann in 1690 but he used this term to refer to a group of plants which form only a subset of what today are known as angiosperms. Hermannn's Angiospermae including only flowering plants possessing seeds enclosed in capsules, distinguished from his Gymnospermae, which were flowering plants with achenial or schizo-carpic fruits, the whole fruit or each of its pieces being here regarded as a seed and naked. The terms Angiospermae and Gymnospermae were used by
Carl Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his Nobility#Ennoblement, ennoblement in 1761 as Carl von Linné#Blunt, Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalise ...
with the same sense, but with restricted application, in the names of the orders of his class Didynamia. The terms angiosperms and gymnosperm fundamentally changed in meaning in 1827 when Robert Brown established the existence of truly naked ovules in the Cycadeae and Coniferae. The term gymnosperm was from then on applied to seed plants with naked ovules, and the term angiosperm to seed plants with enclosed ovules. However, for many years after Brown's discovery, the primary division of the seed plants was seen as between monocots and dicots, with gymnosperms as a small subset of the dicots. In 1851, Hofmeister discovered the changes occurring in the embryo-sac of flowering plants, and determined the correct relationships of these to the Cryptogamia. This fixed the position of Gymnosperms as a class distinct from Dicotyledons, and the term Angiosperm then gradually came to be accepted as the suitable designation for the whole of the flowering plants other than Gymnosperms, including the classes of Dicotyledons and Monocotyledons. This is the sense in which the term is used today. In most taxonomies, the flowering plants are treated as a coherent group. The most popular descriptive name has been Angiospermae, with
Anthophyta The anthophytes are a grouping of plant taxa bearing flower-like reproductive structures. They were formerly thought to be a clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyly, m ...
(lit. 'flower-plants') a second choice (both unranked). The Wettstein system and
Engler system One of the prime list of systems of plant taxonomy, systems of plant taxonomy, the Engler system was devised by Adolf Engler (1844–1930), and is featured in two major taxonomic texts he authored or co-authored. His influence is reflected in the u ...
treated them as a subdivision (Angiospermae). The Reveal system also treated them as a subdivision (Magnoliophytina), but later split it to Magnoliopsida, Liliopsida, and Rosopsida. The
Takhtajan system A list of systems of plant taxonomy, system of plant taxonomy, the Takhtajan system of plant classification was published by Armen Takhtajan, in several versions from the 1950s onwards. It is usually compared to the Cronquist system. It admits Para ...
and
Cronquist system The Cronquist system is a list of systems of plant taxonomy, taxonomic classification system of angiosperms, flowering plants. It was developed by Arthur Cronquist in a series of monographs and texts, including ''The Evolution and Classification of ...
treat them as a division (Magnoliophyta). The
Dahlgren system One of the modern list of systems of plant taxonomy, systems of plant taxonomy, the Dahlgren system was published by monocotyledons, monocot specialist Rolf Dahlgren in 1975 and revised in 1977, and 1980. However, he is best known for his two trea ...
and Thorne system (1992) treat them as a class (Magnoliopsida). The
APG system The APG system (Angiosperm Phylogeny Group system) of plant classification is the first version of a modern, mostly Molecular phylogenetics, molecular-based, list of systems of plant taxonomy, system of plant taxonomy. Published in 1998 by the Angi ...
of 1998, and the later 2003 and 2009 revisions, treat the flowering plants as an unranked clade without a formal Latin name (angiosperms). A formal classification was published alongside the 2009 revision in which the flowering plants rank as a subclass (Magnoliidae). The internal classification of this group has undergone considerable revision. The
Cronquist system The Cronquist system is a list of systems of plant taxonomy, taxonomic classification system of angiosperms, flowering plants. It was developed by Arthur Cronquist in a series of monographs and texts, including ''The Evolution and Classification of ...
, proposed by
Arthur Cronquist Arthur John Cronquist (March 19, 1919 – March 22, 1992) was an American biologist, botany, botanist and a specialist on Compositae. He is considered one of the most influential botanists of the 20th century, largely due to his formulation o ...
in 1968 and published in its full form in 1981, is still widely used but is no longer believed to accurately reflect
phylogeny A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree (graph theory), tree showing the evolutionary relationships among va ...
. A consensus about how the flowering plants should be arranged has recently begun to emerge through the work of the
Angiosperm Phylogeny Group The Angiosperm Phylogeny Group (APG) is an informal international group of systematic botany, botanists who collaborate to establish a consensus on the Taxonomy (biology), taxonomy of flowering plants (angiosperms) that reflects new knowledge abo ...
(APG), which published an influential reclassification of the angiosperms in 1998. Updates incorporating more recent research were published as the
APG II system The APG II system (Angiosperm Phylogeny Group II system) of plant classification is the second, now obsolete, version of a modern, mostly Molecular phylogenetics, molecular-based, list of systems of plant taxonomy, system of plant taxonomy that ...
in 2003, the
APG III system The APG III system of flowering plant classification is the third version of a modern, mostly Molecular phylogenetics, molecular-based, list of systems of plant taxonomy, system of plant taxonomy being developed by the Angiosperm Phylogeny Group ( ...
in 2009, and the
APG IV system The APG IV system of flowering plant classification is the fourth version of a modern, mostly Molecular phylogenetics, molecular-based, list of systems of plant taxonomy, system of plant taxonomy for flowering plants (angiosperms) being develope ...
in 2016. Traditionally, the flowering plants are divided into two groups, * Dicotyledoneae or
Magnoliopsida Magnoliopsida is a valid botanical name for a class (biology), class of flowering plants. By definition the class will include the family Magnoliaceae, but its wiktionary:circumscription, circumscription can otherwise vary, being more inclusive o ...
* Monocotyledoneae or
Liliopsida Liliopsida Batsch (synonym (taxonomy), synonym: Liliatae) is a botanical name for the Class (biology), class containing the Family (biology), family Liliaceae (or Lily Family). It is considered synonymous (or nearly synonymous) with the name monoc ...
to which the Cronquist system ascribes the classes Magnoliopsida (from "
Magnoliaceae The Magnoliaceae () are a flowering plant family, the magnolia family, in the order (biology), order Magnoliales. It consists of two genus, genera: ''Magnolia'' and ''Liriodendron'' (tulip trees). Unlike most Flowering plant, angiosperms, whose ...
") and Liliopsida (from "
Liliaceae The lily family, Liliaceae, consists of about 15 genera and 610 species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is ...
"). Other descriptive names allowed by Article 16 of the
ICBN The ''International Code of Nomenclature for algae, fungi, and plants'' (ICN) is the set of rules and recommendations dealing with the formal botanical names that are given to plants, fungi and a few other groups of organisms, all those "trad ...
include Dicotyledones or Dicotyledoneae, and Monocotyledones or Monocotyledoneae, which have a long history of use. In plain English, their members may be called "dicotyledons" ("dicots") and "monocotyledons" ("monocots"). The Latin behind these names refers the observation that the dicots most often have two
cotyledon A cotyledon (; ; ; , gen. (), ) is a significant part of the embryo within the seed of a plant, and is defined as "the embryonic leaf in seed-bearing plants, one or more of which are the first to appear from a germination, germinating see ...
s, or embryonic leaves, within each seed. The monocots usually have only one, but the rule is not absolute either way. From a broad diagnostic point of view, the number of cotyledons is neither a particularly handy, nor a reliable character. Recent studies, as by the APG, show that the monocots form a
monophyletic In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population Population typically refers to the number of ...
group (a
clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyly, monophyletic – that is, composed of a common ancestor and all its lineage (evolution), lineal descendants – on a phylogenetic tree. ...
) but that the dicots are
paraphyletic In taxonomy, a group is paraphyletic if it consists of the group's last common ancestor and most of its descendants, excluding a few monophyletic subgroups. The group is said to be paraphyletic ''with respect to'' the excluded subgroups. In ...
. Nevertheless, the majority of dicot species fall into a clade, the
eudicots The eudicots, Eudicotidae, or eudicotyledons are a clade of flowering plants mainly characterized by having two seed leaves upon germination. The term derives from Dicotyledons. Traditionally they were called tricolpates or non-magnoliid dicots ...
or tricolpates, and most of the remaining fall into another major clade, the
magnoliids Magnoliids (or Magnoliidae or Magnolianae) are a clade of flowering plants. With more than 10,000 species, including magnolias, nutmeg, bay laurel, cinnamon, avocado, black pepper, tulip tree and many others, it is the third-largest group of angio ...
, containing about 9,000 species. The rest include a paraphyletic grouping of early branching taxa known collectively as the
basal angiosperms The basal angiosperms are the flowering plants which diverged from the lineage leading to most flowering plants. In particular, the most basal (phylogenetics), basal angiosperms were called the ANITA grade, which is made up of ''Amborella'' (a sin ...
, plus the families Ceratophyllaceae and Chloranthaceae.


Modern classification

There are eight groups of living angiosperms: *
Basal angiosperms The basal angiosperms are the flowering plants which diverged from the lineage leading to most flowering plants. In particular, the most basal (phylogenetics), basal angiosperms were called the ANITA grade, which is made up of ''Amborella'' (a sin ...
(ANA: ''Amborella'', Nymphaeales, Austrobaileyales) ** ''
Amborella ''Amborella'' is a monotypic genus of understory shrubs or small trees Endemism, endemic to the main island, Grande Terre (New Caledonia), Grande Terre, of New Caledonia in the southwest Pacific Ocean. The genus is the only member of the family ...
'', a single species of shrub from
New Caledonia ) , anthem = "" , image_map = New Caledonia on the globe (small islands magnified) (Polynesia centered).svg , map_alt = Location of New Caledonia , map_caption = Location of New Caledonia , mapsize = 290px , subdivision_type = Sovereign st ...
; ** Nymphaeales, about 80 species,
Figure 2
water lilies ''Water Lilies'' (or ''Nymphéas'', ) is a series of approximately 250 oil paintings by French Impressionist Impressionism was a 19th-century art movement characterized by relatively small, thin, yet visible brush strokes, open Composit ...
and
Hydatellaceae Hydatellaceae are a family (biology), family of small, aquatic flowering plants. The family consists of tiny, relatively simple plants occurring in Australasia and India. It was formerly considered to be related to the grasses and sedges (order ...
; **
Austrobaileyales Austrobaileyales is an order of flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek language, Greek words ...
, about 100 species of
woody plant A woody plant is a plant that produces wood as its structural tissue and thus has a hard stem. In cold climates, woody plants further survive winter or dry season above ground, as opposite to Herbaceous plant, herbaceous plants that die back to t ...
s from various parts of the world *
Core angiosperms Mesangiospermae (core angiosperms) is a clade of flowering plants (angiosperms), informally called "mesangiosperms". They are one of two main groups of angiosperms. It is a name created under the rules of the ''PhyloCode'' system of phylogenetic ...
(Mesangiospermae) **
Chloranthales Chloranthaceae is a Family (biology), family of flowering plants (angiosperms), the only family in the Order (biology), order Chloranthales. It is not closely related to any other family of flowering plants, and is among the early-diverging lin ...
, 77 known species of aromatic plants with toothed leaves; **
Magnoliids Magnoliids (or Magnoliidae or Magnolianae) are a clade of flowering plants. With more than 10,000 species, including magnolias, nutmeg, bay laurel, cinnamon, avocado, black pepper, tulip tree and many others, it is the third-largest group of angio ...
, about 10,000 species, characterised by
trimerous Merosity (from the greek "méros," which means "having parts") refers to the number of component parts in a distinct whorl of a plant structure. The term is most commonly used in the context of a flower A flower, sometimes known as a bloom or ...
flowers, pollen with one pore, and usually branching-veined leaves—for example
magnolia ''Magnolia'' is a large genus of about 210 to 340The number of species in the genus ''Magnolia'' depends on the taxonomic view that one takes up. Recent molecular and morphology (biology), morphological research shows that former genera ''Talaum ...
s,
bay laurel ''Laurus nobilis'' is an aromatic evergreen tree or large shrub with green, Glossary of botanical terms#glabrous, glabrous (smooth) leaves. It is in the flowering plant family Lauraceae. It is native to the Mediterranean region and is used as ...
, and
black pepper Black pepper (''Piper nigrum'') is a flowering plant, flowering vine in the family Piperaceae, cultivated for its fruit, known as a peppercorn, which is usually dried and used as a spice and seasoning. The fruit is a drupe (stonefruit) which is ...
; **
Monocots Monocotyledons (), commonly referred to as monocots, (Lilianae ''sensu'' Chase & Reveal) are grass and grass-like flowering plants (angiosperms), the seeds of which typically contain only one Embryo#Plant embryos, embryonic leaf, or cotyledon. Th ...
, about 70,000 species, characterised by trimerous flowers, a single
cotyledon A cotyledon (; ; ; , gen. (), ) is a significant part of the embryo within the seed of a plant, and is defined as "the embryonic leaf in seed-bearing plants, one or more of which are the first to appear from a germination, germinating see ...
, pollen with one pore, and usually parallel-veined leaves—for example
grasses Poaceae () or Gramineae () is a large and nearly ubiquitous Family (biology), family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species culti ...
,
orchid Orchids are plants that belong to the Family (biology), family Orchidaceae (), a diverse and widespread group of flowering plants with blooms that are often colourful and fragrant. Along with the Asteraceae, they are one of the two largest fam ...
s, and palms; ** ''
Ceratophyllum ''Ceratophyllum'' is a cosmopolitan genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hie ...
'', about 6 species of
aquatic plant Aquatic plants are plant Plants are predominantly Photosynthesis, photosynthetic eukaryotes of the Kingdom (biology), kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae ...
s, perhaps most familiar as
aquarium An aquarium (plural: ''aquariums'' or ''aquaria'') is a vivarium of any size having at least one transparent side in which aquatic plants or animals are kept and displayed. fishkeeping, Fishkeepers use aquaria to keep fish, invertebrates, amp ...
plants; **
Eudicots The eudicots, Eudicotidae, or eudicotyledons are a clade of flowering plants mainly characterized by having two seed leaves upon germination. The term derives from Dicotyledons. Traditionally they were called tricolpates or non-magnoliid dicots ...
, about 175,000 species, characterised by 4- or 5-merous flowers, pollen with three pores, and usually branching-veined leaves—for example
sunflower The common sunflower (''Helianthus annuus'') is a large annual plant, annual forb of the genus ''Helianthus'' grown as a crop for its Sunflower seed, edible oily seeds. Apart from sunflower oil, cooking oil production, it is also used as livestoc ...
s,
petunia ''Petunia'' is genus of 20 species of flowering plants of South American origin. The popular flower of the same name derived its epithet from the French, which took the word ''petun'', meaning "tobacco," from a Tupi–Guarani language. A tender ...
,
buttercup ''Ranunculus'' is a List of the largest genera of flowering plants, large genus of about almost 1700 to more than 1800 species of flowering plants in the family Ranunculaceae. Members of the genus are known as buttercups, spearworts and water c ...
,
apple An apple is an edible fruit produced by an apple tree (''Malus domestica''). Apple fruit tree, trees are agriculture, cultivated worldwide and are the most widely grown species in the genus ''Malus''. The tree originated in Central Asia, wh ...
s, and
oak An oak is a tree or shrub in the genus ''Quercus'' (; Latin "oak tree") of the beech family, Fagaceae. There are approximately 500 extant species of oaks. The common name "oak" also appears in the names of species in related genera, notably ''L ...
s. The exact relationships among these eight groups is not yet clear, although there is agreement that the first three groups to diverge from the ancestral angiosperm were
Amborellales ''Amborella'' is a monotypic genus of understory shrubs or small trees Endemism, endemic to the main island, Grande Terre (New Caledonia), Grande Terre, of New Caledonia in the southwest Pacific Ocean. The genus is the only member of the family ...
, Nymphaeales, and Austrobaileyales (basal angiosperms) Of the remaining five groups (core angiosperms), the relationships among the three broadest groups remains unclear (magnoliids, monocots, and eudicots). Zeng and colleagues (Fig. 1) describe four competing schemes.The eudicots and monocots are the largest and most diversified, with ~ 75% and 20% of angiosperm species, respectively. Some analyses make the magnoliids the first to diverge, others the monocots. ''Ceratophyllum'' seems to group with the eudicots rather than with the monocots. The APG IV retained the overall higher order relationship described in APG III.


Evolutionary history


Paleozoic

Fossilised
spore In biology, a spore is a unit of sexual reproduction, sexual or asexual reproduction that may be adapted for biological dispersal, dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of ...
s suggest that land plants (
embryophyte The Embryophyta (), or land plants, are the most familiar group of green plants that comprise vegetation on Earth. Embryophytes () have a common ancestor with green algae, having emerged within the Phragmoplastophyta clade of green algae as siste ...
s) have existed for at least 475 million years. Early land plants reproduced sexually with flagellated, swimming sperm, like the green algae from which they evolved. An adaptation to terrestrialization was the development of upright
sporangia A sporangium (; from Late Latin, ) is an enclosure in which spores are formed. It can be composed of a unicellular organism, single cell or can be multicellular organism, multicellular. Virtually all plants, fungus, fungi, and many other l ...
for dispersal by
spore In biology, a spore is a unit of sexual reproduction, sexual or asexual reproduction that may be adapted for biological dispersal, dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of ...
s to new habitats. This feature is lacking in the descendants of their nearest algal relatives, the Charophycean green algae. A later terrestrial adaptation took place with retention of the delicate, avascular sexual stage, the gametophyte, within the tissues of the vascular sporophyte. This occurred by spore germination within sporangia rather than spore release, as in non-seed plants. A current example of how this might have happened can be seen in the precocious spore germination in ''
Selaginella ''Selaginella'' is the sole genus of vascular plants in the family Selaginellaceae, the spikemosses or lesser clubmosses. This family is distinguished from Lycopodiaceae (the clubmosses) by having scale-leaves bearing a ligule and by having h ...
'', the spike-moss. The result for the ancestors of angiosperms and gymnosperms was enclosing the female gamete in a case, the seed. The first seed bearing plants were gymnosperms, like the
ginkgo ''Ginkgo'' is a genus of non-flowering seed plants. The scientific name is also used as the English name. The order to which it belongs, Ginkgoales, first appeared in the Permian, 270 million years ago, and is now the only living genus within t ...
, and
conifer Conifers are a group of conifer cone, cone-bearing Spermatophyte, seed plants, a subset of gymnosperms. Scientifically, they make up the phylum, division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single ...
s (such as
pine A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family (biology), family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae. The World Flora Online created by the Royal Botanic Gardens, Kew and Missouri Botanic ...
s and firs). These did not produce flowers. The pollen grains (male gametophytes) of ''Ginkgo'' and cycads produce a pair of flagellated, mobile sperm cells that "swim" down the developing pollen tube to the female and her eggs. Angiosperms appear suddenly and in great diversity in the fossil record in the Early Cretaceous. This poses such a problem for the theory of gradual
evolution Evolution is change in the heredity, heritable Phenotypic trait, characteristics of biological populations over successive generations. These characteristics are the Gene expression, expressions of genes, which are passed on from parent to ...
that
Charles Darwin Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all species of life have descended ...
called it an "abominable mystery". Several groups of extinct gymnosperms, in particular
seed fern A seed is an Plant embryogenesis, embryonic plant enclosed in a testa (botany), protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, includ ...
s, have been proposed as the
ancestors An ancestor, also known as a forefather, fore-elder or a forebear, is a parent or (Recursion, recursively) the parent of an antecedent (i.e., a grandparent, great-grandparent, great-great-grandparent and so forth). ''Ancestor'' is "any person ...
of flowering plants, but there is no continuous fossil evidence showing how flowers evolved, and botanists still regard it as a mystery. Several claims of pre-Cretaceous angiosperm fossils have been made, such as the upper
Triassic The Triassic ( ) is a geologic period and system (stratigraphy), system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago (Year#Abbreviations yr and ya, Mya), to the beginning of the Jurassic Period 201.36 ...
'' Sanmiguelia lewisi'', but none of these are widely accepted by paleobotanists. Oleanane, a
secondary metabolite Secondary metabolites, also called specialised metabolites, toxins, secondary products, or natural products, are organic compounds produced by any lifeform, e.g. bacteria, fungi, animals, or plants, which are not directly involved in the norma ...
produced by many flowering plants, has been found in
Permian The Permian ( ) is a geologic period and System (stratigraphy), stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last ...
deposits of that age together with fossils of gigantopterids. Gigantopterids are a group of extinct seed plants that share many morphological traits with flowering plants, although they are not known to have been flowering plants themselves. Molecular evidence suggests that the ancestors of angiosperms diverged from the gymnosperms during the late
Devonian The Devonian ( ) is a period (geology), geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Dev ...
, about 365 million years ago, despite only appearing in the fossil record during the Early Cretaceous, almost two hundred million years later.


Triassic and Jurassic

Based on fossil evidence, some have proposed that the ancestors of the angiosperms diverged from an unknown group of gymnosperms in the Triassic period (245–202 million years ago). Fossil angiosperm-like pollen from the Middle Triassic (247.2–242.0 Ma) suggests an older date for their origin, which is further supported by genetic evidence of the ancestors of angiosperms diverging during the Devonian. A close relationship between angiosperms and gnetophytes, proposed on the basis of morphological evidence, has more recently been disputed on the basis of molecular evidence that suggest gnetophytes are instead more closely related to conifers and other gymnosperms. The fossil plant species ''Nanjinganthus dendrostyla'' from
Early Jurassic The Early Jurassic Epoch (geology), Epoch (in chronostratigraphy corresponding to the Lower Jurassic series (stratigraphy), Series) is the earliest of three epochs of the Jurassic Period. The Early Jurassic starts immediately after the Triassic-J ...
China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's List of countries and dependencies by population, most populous country, with a Population of China, population exceeding 1.4 billion, slig ...
seems to share many exclusively angiosperm features, such as a thickened receptacle with
ovule In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: the ''integument'', forming its outer layer, the ''nucellus'' (or remnant of the sporangium, megasporangium), ...
s, and thus might represent a crown-group or a
stem-group In phylogenetics, the crown group or crown assemblage is a collection of species composed of the living representatives of the collection, the most recent common ancestor of the collection, and all descendants of the most recent common ancestor. ...
angiosperm. However, these have been disputed by other researchers, who contend that the structures are misinterpreted decomposed conifer cones. The evolution of seed plants and later angiosperms appears to be the result of two distinct rounds of
whole genome duplication Paleopolyploidy is the result of genome duplications which occurred at least several million years ago (MYA). Such an event could either double the genome of a single species ( autopolyploidy) or combine those of two species (allopolyploidy ...
events. These occurred at and . Another possible whole genome duplication event at perhaps created the ancestral line that led to all modern flowering plants. That event was studied by sequencing the genome of an ancient flowering plant, '' Amborella trichopoda.'' One study has suggested that the early-middle
Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The J ...
plant '' Schmeissneria'', traditionally considered a type of ginkgo, may be the earliest known angiosperm, or at least a close relative. This, along with all other pre-Cretaceous angiosperm fossil claims, is strongly disputed by many paleobotanists. Many paleobotanists consider the Caytoniales, a group of " seed ferns" that first appeared during the Triassic and went extinct in the Cretaceous, to be amongst the best candidates for a close relative of angiosperms.


Cretaceous

Whereas the earth had previously been dominated by ferns and conifers, angiosperms quickly spread during the Cretaceous. They now comprise about 90% of all plant species including most food crops. It has been proposed that the swift rise of angiosperms to dominance was facilitated by a reduction in their genome size. During the early Cretaceous period, only angiosperms underwent rapid genome downsizing, while genome sizes of ferns and gymnosperms remained unchanged. Smaller genomes—and smaller nuclei—allow for faster rates of cell division and smaller cells. Thus, species with smaller genomes can pack more, smaller cells—in particular veins and stomata—into a given leaf volume. Genome downsizing therefore facilitated higher rates of leaf gas exchange (transpiration and photosynthesis) and faster rates of growth. This would have countered some of the negative physiological effects of genome duplications, facilitated increased uptake of carbon dioxide despite concurrent declines in atmospheric CO2 concentrations, and allowed the flowering plants to outcompete other land plants. The oldest known fossils definitively attributable to angiosperms are reticulated monosulcate pollen from the late
Valanginian In the geologic timescale The geologic time scale, or geological time scale, (GTS) is a representation of time based on the Geologic record, rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the proc ...
(Early or Lower Cretaceous - 140 to 133 million years ago) of Italy and Israel, likely representative of the basal angiosperm grade. The earliest known macrofossil confidently identified as an angiosperm, '' Archaefructus liaoningensis'', is dated to about 125 million years BP (the
Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 79 million years, it is the long ...
period), whereas pollen considered to be of angiosperm origin takes the
fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
record back to about 130 million years BP, with '' Montsechia'' representing the earliest flower at that time. In 2013 flowers encased in amber were found and dated 100 million years before present. The amber had frozen the act of sexual reproduction in the process of taking place. Microscopic images showed tubes growing out of pollen and penetrating the flower's stigma. The pollen was sticky, suggesting it was carried by insects. In August 2017, scientists presented a detailed description and 3D model image of what the first flower possibly looked like, and presented the hypothesis that it may have lived about 140 million years ago. A Bayesian analysis of 52 angiosperm taxa suggested that the crown group of angiosperms evolved between and . Recent DNA analysis based on
molecular systematics Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...
showed that ''Amborella trichopoda'', found on the Pacific island of
New Caledonia ) , anthem = "" , image_map = New Caledonia on the globe (small islands magnified) (Polynesia centered).svg , map_alt = Location of New Caledonia , map_caption = Location of New Caledonia , mapsize = 290px , subdivision_type = Sovereign st ...
, belongs to a
sister group In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and t ...
of the other flowering plants, and morphological studies suggest that it has features that may have been characteristic of the earliest flowering plants. The orders
Amborellales ''Amborella'' is a monotypic genus of understory shrubs or small trees Endemism, endemic to the main island, Grande Terre (New Caledonia), Grande Terre, of New Caledonia in the southwest Pacific Ocean. The genus is the only member of the family ...
, Nymphaeales, and
Austrobaileyales Austrobaileyales is an order of flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek language, Greek words ...
diverged as separate lineages from the remaining angiosperm clade at a very early stage in flowering plant evolution. The great angiosperm
radiation In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. This includes: * ''electromagnetic radiation'', such as radio waves, microwaves, infrared, visib ...
, when a great diversity of angiosperms appears in the fossil record, occurred in the mid-
Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 79 million years, it is the long ...
(approximately 100 million years ago). However, a study in 2007 estimated that the division of the five most recent of the eight main groups occurred around 140 million years ago. (the genus ''
Ceratophyllum ''Ceratophyllum'' is a cosmopolitan genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hie ...
'', the family Chloranthaceae, the
eudicots The eudicots, Eudicotidae, or eudicotyledons are a clade of flowering plants mainly characterized by having two seed leaves upon germination. The term derives from Dicotyledons. Traditionally they were called tricolpates or non-magnoliid dicots ...
, the
magnoliids Magnoliids (or Magnoliidae or Magnolianae) are a clade of flowering plants. With more than 10,000 species, including magnolias, nutmeg, bay laurel, cinnamon, avocado, black pepper, tulip tree and many others, it is the third-largest group of angio ...
, and the
monocots Monocotyledons (), commonly referred to as monocots, (Lilianae ''sensu'' Chase & Reveal) are grass and grass-like flowering plants (angiosperms), the seeds of which typically contain only one Embryo#Plant embryos, embryonic leaf, or cotyledon. Th ...
) . It is generally assumed that the function of flowers, from the start, was to involve mobile animals in their reproduction processes. That is, pollen can be scattered even if the flower is not brightly colored or oddly shaped in a way that attracts animals; however, by expending the energy required to create such traits, angiosperms can enlist the aid of animals and, thus, reproduce more efficiently. Island genetics provides one proposed explanation for the sudden, fully developed appearance of flowering plants. Island genetics is believed to be a common source of
speciation Speciation is the evolutionary process by which populations evolve to become distinct species. The biologist Orator F. Cook coined the term in 1906 for cladogenesis, the splitting of lineages, as opposed to anagenesis, phyletic evolution within ...
in general, especially when it comes to radical adaptations that seem to have required inferior transitional forms. Flowering plants may have evolved in an isolated setting like an
island An island (or isle) is an isolated piece of habitat that is surrounded by a dramatically different habitat, such as water. Very small islands such as emergent land features on atolls can be called islets, skerries, cays or keys. An island ...
or island chain, where the plants bearing them were able to develop a highly specialised relationship with some specific animal (a
wasp A wasp is any insect of the narrow-waisted suborder Apocrita of the order Hymenoptera which is neither a bee nor an ant; this excludes the broad-waisted sawflies (Symphyta), which look somewhat like wasps, but are in a separate suborder. ...
, for example). Such a relationship, with a hypothetical wasp carrying pollen from one plant to another much the way
fig wasp Fig wasps are wasps of the superfamily Chalcidoidea which spend their larval stage inside ficus, figs. Most are pollinators but others simply feed off the plant. The non-pollinators belong to several groups within the superfamily Chalcidoidea, whi ...
s do today, could result in the development of a high degree of specialisation in both the plant(s) and their partners. Note that the wasp example is not incidental;
bees Bees are winged insects closely related to wasps and ants, known for their roles in pollination and, in the case of the best-known bee species, the western honey bee, for producing honey. Bees are a monophyly, monophyletic lineage within the ...
, which, it is postulated, evolved specifically due to mutualistic plant relationships, are descended from wasps. Animals are also involved in the distribution of seeds. Fruit, which is formed by the enlargement of flower parts, is frequently a seed-dispersal tool that attracts animals to eat or otherwise disturb it, incidentally scattering the seeds it contains (see frugivory). Although many such mutualistic relationships remain too fragile to survive
competition Competition is a rivalry where two or more parties strive for a common goal which cannot be shared: where one's gain is the other's loss (an example of which is a zero-sum game). Competition can arise between entities such as organisms, ind ...
and to spread widely, flowering proved to be an unusually effective means of reproduction, spreading (whatever its origin) to become the dominant form of land plant life. Flower
ontogeny Ontogeny (also ontogenesis) is the origination and development of an organism (both physical and psychological, e.g., moral development), usually from the time of fertilization of the ovum, egg to adult. The term can also be used to refer to t ...
uses a combination of
gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian inheritance#History, Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanin ...
s normally responsible for forming new shoots. The most primitive flowers probably had a variable number of flower parts, often separate from (but in contact with) each other. The flowers tended to grow in a spiral pattern, to be bisexual (in plants, this means both male and female parts on the same flower), and to be dominated by the
ovary The ovary is an organ in the female reproductive system that produces an ovum. When released, this travels down the fallopian tube into the uterus, where it may become fertilized by a sperm. There is an ovary () found on each side of the bo ...
(female part). As flowers evolved, some variations developed parts fused together, with a much more specific number and design, and with either specific sexes per flower or plant or at least "ovary-inferior". Flower evolution continues to the present day; modern flowers have been so profoundly influenced by humans that some of them cannot be pollinated in nature. Many modern domesticated flower species were formerly simple weeds, which sprouted only when the ground was disturbed. Some of them tended to grow with human crops, perhaps already having symbiotic
companion plant Companion planting in gardening and agriculture is the planting of different crops in proximity for any of a number of different reasons, including pest control, pollination, providing habitat for beneficial insects, maximizing use of space, and ...
relationships with them, and the prettiest did not get plucked because of their beauty, developing a dependence upon and special adaptation to human affection. A few
paleontologists Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene The Holocene ( ) is the current geological epoch. It began approximate ...
have also proposed that flowering plants, or angiosperms, might have evolved due to interactions with dinosaurs. One of the idea's strongest proponents is Robert T. Bakker. He proposes that
herbivorous A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...
dinosaurs, with their eating habits, provided a selective pressure on plants, for which adaptations either succeeded in deterring or coping with predation by herbivores. By the late Cretaceous, angiosperms appear to have dominated environments formerly occupied by
fern A fern (Polypodiopsida or Polypodiophyta ) is a member of a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers. The Polypodiophyta, polypodiophytes include all living pteridop ...
s and cycadophytes, but large canopy-forming trees replaced
conifer Conifers are a group of conifer cone, cone-bearing Spermatophyte, seed plants, a subset of gymnosperms. Scientifically, they make up the phylum, division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single ...
s as the dominant trees only close to the end of the Cretaceous 66 million years ago or even later, at the beginning of the
Paleogene The Paleogene ( ; British English, also spelled Palaeogene or Palæogene; informally Lower Tertiary or Early Tertiary) is a geologic period, geologic period and system that spans 43 million years from the end of the Cretaceous Period million yea ...
. The radiation of herbaceous angiosperms occurred much later. Yet, many fossil plants recognisable as belonging to modern families (including
beech Beech (''Fagus'') is a genus of deciduous trees in the family Fagaceae, native to temperate Europe, Asia, and North America. Recent classifications recognize 10 to 13 species in two distinct subgenera, ''Engleriana'' and ''Fagus''. The ''Engle ...
,
oak An oak is a tree or shrub in the genus ''Quercus'' (; Latin "oak tree") of the beech family, Fagaceae. There are approximately 500 extant species of oaks. The common name "oak" also appears in the names of species in related genera, notably ''L ...
,
maple ''Acer'' () is a genus of trees and shrubs commonly known as maples. The genus is placed in the family Sapindaceae.Stevens, P. F. (2001 onwards). Angiosperm Phylogeny Website. Version 9, June 2008 nd more or less continuously updated since h ...
, and
magnolia ''Magnolia'' is a large genus of about 210 to 340The number of species in the genus ''Magnolia'' depends on the taxonomic view that one takes up. Recent molecular and morphology (biology), morphological research shows that former genera ''Talaum ...
) had already appeared by the late Cretaceous. Flowering plants appeared in Australia about 126 million years ago. This also pushed the age of ancient Australian vertebrates, in what was then a south polar continent, to 126-110 million years old.


Gallery of photos

Asteracea poster 3.jpg, A poster of twelve different species of flowers of the family Asteraceae Lupinus-pilosus-2015-Zachi-Evenor-cropped01.jpg, '' Lupinus pilosus'' Rose bud.jpg,
Bud In botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the A ...
of a pink
rose A rose is either a woody perennial plant, perennial flowering plant of the genus ''Rosa'' (), in the family Rosaceae (), or the flower it bears. There are over three hundred Rose species, species and Garden roses, tens of thousands of cultivar ...


Diversity

The number of species of flowering plants is estimated to be in the range of 250,000 to 400,000. This compares to around 12,000 species of
moss Mosses are small, non-vascular flower A flower, sometimes known as a bloom or blossom, is the reproduction, reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to ...
and 11,000 species of
pteridophytes A pteridophyte is a vascular plant Vascular plants (), also called tracheophytes () or collectively Tracheophyta (), form a large group of embryophyte, land plants ( accepted known species) that have lignin, lignified tissue (biology), tissues ...
, showing that flowering plants are much more diverse. The number of
families Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...
in APG (1998) was 462. In
APG II The APG II system (Angiosperm Phylogeny Group II system) of plant classification is the second, now obsolete, version of a modern, mostly Molecular phylogenetics, molecular-based, list of systems of plant taxonomy, system of plant taxonomy that ...
(2003) it is not settled; at maximum it is 457, but within this number there are 55 optional segregates, so that the minimum number of families in this system is 402. In
APG III The APG III system of flowering plant classification is the third version of a modern, mostly molecular-based, system of plant taxonomy being developed by the Angiosperm Phylogeny Group (APG). Published in 2009, it was superseded in 2016 by a f ...
(2009) there are 415 families. Compared to the APG III system, the
APG IV The APG IV system of flowering plant classification is the fourth version of a modern, mostly Molecular phylogenetics, molecular-based, list of systems of plant taxonomy, system of plant taxonomy for flowering plants (angiosperms) being develope ...
system recognizes five new orders (Boraginales, Dilleniales, Icacinales, Metteniusales and Vahliales), along with some new families, making a total of 64 angiosperm orders and 416 families. The diversity of flowering plants is not evenly distributed. Nearly all species belong to the eudicot (75%), monocot (23%), and magnoliid (2%) clades. The remaining five clades contain a little over 250 species in total; i.e. less than 0.1% of flowering plant diversity, divided among nine families. The 43 most diverse of 443 families of flowering plants by species, in their APG circumscriptions, are #
Asteraceae The family (biology), family Asteraceae, alternatively Compositae, consists of over 32,000 known species of flowering plants in over 1,900 genera within the Order (biology), order Asterales. Commonly referred to as the aster, daisy, composite, ...
or Compositae ( daisy family): 22,750 species; #
Orchidaceae Orchids are plants that belong to the Family (biology), family Orchidaceae (), a diverse and widespread group of flowering plants with blooms that are often colourful and fragrant. Along with the Asteraceae, they are one of the two largest fam ...
(orchid family): 21,950; #
Fabaceae The Fabaceae or Leguminosae,International Code of Nomenc ...
or Leguminosae (
bean A bean is the seed of several plants in the family Fabaceae The Fabaceae or Leguminosae,Rubiaceae The Rubiaceae are a family (biology), family of flowering plants, commonly known as the coffee, madder, or bedstraw family. It consists of terrestrial trees, shrubs, lianas, or herbs that are recognizable by simple, opposite leaves with Petiole ...
( madder family): 13,150; #
Poaceae Poaceae () or Gramineae () is a large and nearly ubiquitous Family (biology), family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species culti ...
or Gramineae (grass family): 10,035; #
Lamiaceae The Lamiaceae ( ) or Labiatae are a family (biology), family of flowering plants commonly known as the mint, deadnettle or sage family. Many of the plants are aromatic in all parts and include widely used culinary herbs like basil (herb), basil ...
or Labiatae (
mint MiNT is Now TOS (MiNT) is a free software alternative operating system Kernel (operating system), kernel for the Atari ST system and its successors. It is a multi-tasking alternative to Atari TOS, TOS and MagiC. Together with the free system co ...
family): 7,175; #
Euphorbiaceae Euphorbiaceae, the spurge family, is a large family of flowering plants. In English, they are also commonly called euphorbias, which is also the name of Euphorbia, a genus in the family. Most spurges, such as ''Euphorbia paralias'', are herbs, b ...
(
spurge ''Euphorbia'' is a very large and diverse genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In ...
family): 5,735; #
Melastomataceae Melastomataceae is a family of dicotyledonous The dicotyledons, also known as dicots (or, more rarely, dicotyls), are one of the two groups into which all the flowering plants (angiosperms) were formerly divided. The name refers to one of t ...
or Melastomaceae ( melastome family): 5,005; #
Myrtaceae Myrtaceae, the myrtle family, is a family of dicotyledonous plants placed within the order Myrtales. Myrtus, Myrtle, Metrosideros, pōhutukawa, Pimenta racemosa, bay rum tree, clove, guava, Acca (plant), acca (feijoa), allspice, and eucalyptus a ...
( myrtle family): 4,625; #
Apocynaceae Apocynaceae (from '' Apocynum'', Greek for "dog-away") is a family of flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derive ...
(
dogbane Dogbane, dog-bane (plant), bane, dog's bane, and other variations, some of them regional and some transient, are names for certain plants that are reputed to kill or repel dogs; "Bane (plant), bane" originally meant "slayer", and was later appli ...
family): 4,555; #
Cyperaceae The Cyperaceae are a family of graminoid (grass-like), monocotyledonous flowering plants known as sedges. The Family (biology), family is large, with some 5,500 known species described in about 90 genera, the largest being the "true sedges" g ...
(
sedge The Cyperaceae are a family of graminoid (grass-like), monocotyledonous flowering plants known as sedges. The Family (biology), family is large, with some 5,500 known species described in about 90 genera, the largest being the "true sedges" g ...
family): 4,350; #
Malvaceae Malvaceae, or the mallows, is a family of flowering plants estimated to contain 244 genera with 4225 known species. Well-known members of economic importance include okra, cotton, Theobroma cacao, cacao and durian. There are also some genera conta ...
( mallow family): 4,225; #
Araceae The Araceae are a family (biology), family of monocotyledonous flowering plants in which flowers are borne on a type of inflorescence called a spadix (botany), spadix. The spadix is usually accompanied by, and sometimes partially enclosed in, a s ...
(
arum ''Arum'' is a genus of flowering plants in the family Araceae, native plant, native to Europe, northern Africa, and western and central Asia, with the highest species diversity in the Mediterranean region. Frequently called arum lilies, they ar ...
family): 4,025; #
Ericaceae The Ericaceae are a Family (biology), family of flowering plants, commonly known as the heath or heather family, found most commonly in acidic and infertile growing conditions. The family is large, with c.4250 known species spread across 124 ge ...
(
heath A heath () is a shrubland habitat (ecology), habitat found mainly on free-draining infertile, acidic soils and characterised by open, low-growing woody vegetation. Moorland is generally related to high-ground heaths with—especially in Great B ...
family): 3,995; # Gesneriaceae ( gesneriad family): 3,870; #
Apiaceae Apiaceae or Umbelliferae is a family of mostly aromatic flowering plants named after the type genus ''Apium'' and commonly known as the celery, carrot or parsley family, or simply as umbellifers. It is the 16th-largest family of flowering plants ...
or Umbelliferae (
parsley Parsley, or garden parsley (''Petroselinum crispum'') is a species of flowering plant in the family Apiaceae that is native to the central and eastern Mediterranean region (Sardinia, Lebanon, Israel, Cyprus, Turkey, southern Italy, Greece, Por ...
family): 3,780; #
Brassicaceae Brassicaceae () or (the older) Cruciferae () is a medium-sized and economically important Family (biology), family of flowering plants commonly known as the mustards, the crucifers, or the cabbage family. Most are herbaceous plants, while some ar ...
or Cruciferae (
cabbage Cabbage, comprising several cultivars of ''Brassica oleracea'', is a leafy green, red (purple), or white (pale green) biennial plant grown as an Annual plant, annual vegetable crop for its dense-leaved heads. It is descended from the wild cabb ...
family): 3,710: #
Piperaceae The Piperaceae (), also known as the pepper family, are a large family of flowering plants. The group contains roughly 3,600 currently accepted species in 5 genera. The vast majority of species can be found within the two main genera: '' Piper' ...
( pepper family): 3,600; #
Bromeliaceae The Bromeliaceae (the bromeliads) are a Family (biology), family of monocot flowering plants of about 80 genera and 3700 known species, native mainly to the Tropics, tropical Americas, with several species found in the American subtropics and on ...
( bromeliad family): 3,540; #
Acanthaceae Acanthaceae is a Family (biology), family (the acanthus family) of dicotyledonous flowering plants containing almost 250 genera and about 2500 species. Most are Tropics, tropical Herbaceous plant, herbs, shrubs, or twining vines; some are epiphyt ...
( acanthus family): 3,500; #
Rosaceae Rosaceae (), the rose family, is a medium-sized family (biology), family of flowering plants that includes 4,828 known species in 91 genera. The name is derived from the type genus ''Rose, Rosa''. Among the most species-rich genera are ''Alche ...
(
rose A rose is either a woody perennial plant, perennial flowering plant of the genus ''Rosa'' (), in the family Rosaceae (), or the flower it bears. There are over three hundred Rose species, species and Garden roses, tens of thousands of cultivar ...
family): 2,830; #
Boraginaceae Boraginaceae, the borage or forget-me-not ''Myosotis'' ( ) is a genus of flowering plants in the family Boraginaceae. The name comes from the Ancient Greek "mouse's ear", which the foliage is thought to resemble. In the northern hemisphere ...
(
borage Borage ( or ; ''Borago officinalis''), also known as starflower, is an annual herb in the flowering plant family Boraginaceae. It is native to the Mediterranean region, and has naturalized in many other locales. It grows satisfactorily in gard ...
family): 2,740; #
Urticaceae The Urticaceae are a family (biology), family, the nettle family, of flowering plants. The family name comes from the genus ''Urtica''. The Urticaceae include a number of well-known and useful plants, including nettles in the genus ''Urtica'', ...
(nettle family): 2,625; #
Ranunculaceae Ranunculaceae (buttercup or crowfoot family; Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then ...
(
buttercup ''Ranunculus'' is a List of the largest genera of flowering plants, large genus of about almost 1700 to more than 1800 species of flowering plants in the family Ranunculaceae. Members of the genus are known as buttercups, spearworts and water c ...
family): 2,525; #
Lauraceae Lauraceae, or the laurels, is a plant Family (biology), family that includes the bay laurel, true laurel and its closest relatives. This family comprises about 2850 known species in about 45 genus (biology), genera worldwide (Christenhusz & Byn ...
( laurel family): 2,500; #
Solanaceae The Solanaceae , or nightshades, are a family (biology), family of flowering plants that ranges from Annual plant, annual and perennial herbs to vines, lianas, epiphytes, shrubs, and trees, and includes a number of agricultural crops, medicinal ...
(
nightshade The Solanaceae , or nightshades, are a family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose ...
family): 2,460; #
Campanulaceae The family (biology), family Campanulaceae (also bellflower family), of the order (biology), order Asterales, contains nearly 2400 species in 84 genus, genera of herbaceous plant, herbaceous flowering plant, plants, shrubs, and rarely small trees ...
( bellflower family): 2,380; #
Arecaceae The Arecaceae is a family (biology), family of Perennial plant, perennial flowering plants in the Monocotyledon, monocot order (biology), order Arecales. Their growth form can be climbing palm, climbers, Shrub, shrubs, tree-like and stemless p ...
(
palm Palm most commonly refers to: * Palm of the hand, the central region of the front of the hand * Palm plants, of family Arecaceae **List of Arecaceae genera * Several Arecaceae#Other plants, other plants known as "palm" Palm or Palms may also refer ...
family): 2,361; #
Annonaceae The Annonaceae are a Family (biology), family of flowering plants consisting of trees, shrubs, or rarely lianas commonly known as the custard apple family or soursop family. With 108 accepted genera and about 2400 known species, it is the largest ...
(
custard apple Custard apple is a common name for a fruit and for the tree that bears it, ''Annona reticulata.'' The tree’s fruits vary in shape; they may be heart-shaped, spherical, oblong or irregular. Their size ranges from 7 to 12 cm (2.8 to 4.7 i ...
family): 2,220; #
Caryophyllaceae Caryophyllaceae, commonly called the pink family or carnation family, is a family (biology), family of flowering plants. It is included in the dicotyledon order Caryophyllales in the APG III system, alongside 33 other families, including Amaranth ...
(
pink Pink is the color of Dianthus plumarius, a namesake flower that is a pale tint of red. It was first used as a color name in the late 17th century. According to surveys in Europe and the United States, pink is the color most often associated with ...
family): 2,200; #
Orobanchaceae Orobanchaceae, the broomrapes, is a family (biology), family of mostly parasitic plants of the order (biology), order Lamiales, with about 90 genus, genera and more than 2000 species. Many of these genera (e.g., ''Pedicularis'', ''Rhinanthus'', ...
( broomrape family): 2,060; #
Amaranthaceae Amaranthaceae is a family of flowering plants commonly known as the amaranth family, in reference to its type (biology), type genus ''Amaranthus''. It includes the former goosefoot family Chenopodiaceae and contains about 165 genera and 2,040 spe ...
(
amaranth ''Amaranthus'' is a cosmopolitan distribution, cosmopolitan genus of annual plant, annual or short-lived perennial plants collectively known as amaranths. Some amaranth species are cultivated as leaf vegetables, pseudocereals, and ornamental pl ...
family): 2,050; #
Iridaceae Iridaceae is a family of plants in order Asparagales, taking its name from the Iris (plant), irises, meaning rainbow, referring to its many colours. There are 66 accepted genera with a total of c. 2244 species worldwide (Christenhusz & Byng 2016 ...
(
iris Iris most often refers to: *Iris (anatomy) In humans and most mammals and birds, the iris (plural: ''irides'' or ''irises'') is a thin, annular structure in the eye, responsible for controlling the diameter and size of the pupil, and thus the a ...
family): 2,025; #
Aizoaceae The Aizoaceae, or fig-marigold family, is a large Family (biology), family of dicotyledonous flowering plants containing 135 genus, genera and about 1800 species. They are commonly known as ice plants or carpet weeds. They are often called vygies ...
or Ficoidaceae ( ice plant family): 2,020; #
Rutaceae The Rutaceae is a family (biology), family, commonly known as the rueRUTACEAE
in BoDD ...
( rue family): 1,815; #
Phyllanthaceae Phyllanthaceae is a family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to m ...
(
phyllanthus ''Phyllanthus'' is the largest genus in the plant family Phyllanthaceae. Estimates of the number of species in this genus vary widely, from 750David J. Mabberley. 2008. ''Mabberley's Plant-Book.'' third edition (2008). Cambridge University P ...
family): 1,745; #
Scrophulariaceae The Scrophulariaceae are a family (biology), family of flowering plants, commonly known as the figwort family. The plants are annual and perennial herbs, as well as shrubs. Flowers have bilateral (zygomorphic) or rarely radial (actinomorphic) ...
( figwort family): 1,700; #
Gentianaceae Gentianaceae is a family of flowering plants of 103 genera and about 1600 species. Etymology The family takes its name from the genus ''Gentiana'', named after the Illyrian king Gentius. Distribution Distribution is cosmopolitan (species), cosm ...
(
gentian ''Gentiana'' is a genus of flowering plants belonging to the gentian family (biology), family (Gentianaceae), the tribe Gentianeae, and the Monophyly, monophyletic subtribe Gentianinae. With about 400 species it is considered a large genus. The ...
family): 1,650; #
Convolvulaceae Convolvulaceae (), commonly called the bindweed, bindweeds or morning glory, morning glories, is a Family (biology), family of about 60 genera and more than 1,650 species. These species are primarily herbaceous vines, but also include trees, sh ...
(
bindweed Bindweed may refer to: * Some species of Convolvulaceae (bindweed family or morning glory family): ** ''Calystegia'' (bindweed, false bindweed, morning glory), a genus of about 25 species of flowering plants ** ''Convolvulus'' (bindweed, morning ...
family): 1,600; #
Proteaceae The Proteaceae form a family (biology), family of flowering plants predominantly distributed in the Southern Hemisphere. The family comprises 83 genus, genera with about 1,660 known species. Together with the Platanaceae and Nelumbonaceae, they ...
(
protea ''Protea'' () is a genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biologi ...
family): 1,600; #
Sapindaceae The Sapindaceae are a family (biology), family of flowering plants in the order Sapindales known as the soapberry family. It contains 138 genera and 1858 accepted species. Examples include Aesculus, horse chestnut, maples, ackee and lychee. The ...
(
soapberry Soapberry is a common name for several plants and may refer to: * Plants in the genus ''Sapindus'', native to warm temperate to tropical regions in both the Old World and the New World. The Berry (botany), berries of these plants contain a natural ...
family): 1,580; #
Cactaceae A cactus (, or less commonly, cactus) is a member of the plant family Cactaceae, a family comprising about 127 genera with some 1750 known species of the order Caryophyllales. The word ''cactus'' derives, through Latin, from the Ancient Greek ...
(
cactus A cactus (, or less commonly, cactus) is a member of the plant family Cactaceae, a family comprising about 127 genera with some 1750 known species of the order Caryophyllales. The word ''cactus'' derives, through Latin, from the Ancient Greek ...
family): 1,500; #
Araliaceae The Araliaceae are a family of flowering plants composed of about 43 genera and around 1500 species consisting of primarily woody plants and some herbaceous plants. The morphology of Araliaceae varies widely, but it is predominantly distinguis ...
('' Aralia'' or
ivy ''Hedera'', commonly called ivy (plural ivies), is a genus of 12–15 species of evergreen In botany, an evergreen is a plant which has Leaf, foliage that remains green and functional through more than one growing season. This also pertains ...
family): 1,450. Of these, the Orchidaceae, Poaceae, Cyperaceae, Araceae, Bromeliaceae, Arecaceae, and Iridaceae are monocot families; Piperaceae, Lauraceae, and Annonaceae are magnoliid dicots; the rest of the families are eudicots.


Reproduction


Fertilisation and embryogenesis

Double fertilization Double fertilization is a complex fertilization mechanism of flowering plants (angiosperms). This process involves the joining of a female gametophyte (Gametophyte#Heteromorphy, megagametophyte, also called the embryo sac) with two male gametes ...
refers to a process in which two sperm cells fertilise cells in the ovule. This process begins when a
pollen Pollen is a powdery substance produced by Spermatophyte, seed plants. It consists of pollen grains (highly reduced microgametophytes), which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects ...
grain adheres to the stigma of the
pistil Gynoecium (; ) is most commonly used as a collective term for the parts of a flower that produce ovules and ultimately develop into the fruit and seeds. The gynoecium is the innermost whorl (botany), whorl of a flower; it consists of (one or m ...
(female reproductive structure), germinates, and grows a long
pollen tube A pollen tube is a tubular structure produced by the male gametophyte of seed plants when it germinates. Pollen tube elongation is an integral stage in the plant life cycle. The pollen tube acts as a conduit to transport the male gamete cells fro ...
. While this pollen tube is growing, a haploid generative cell travels down the tube behind the tube nucleus. The generative cell divides by mitosis to produce two haploid (''n'') sperm cells. As the pollen tube grows, it makes its way from the stigma, down the style and into the ovary. Here the pollen tube reaches the micropyle of the ovule and digests its way into one of the synergids, releasing its contents (which include the sperm cells). The synergid that the cells were released into degenerates and one sperm makes its way to fertilise the egg cell, producing a diploid (2''n'') zygote. The second sperm cell fuses with both central cell nuclei, producing a triploid (3''n'') cell. As the zygote develops into an embryo, the triploid cell develops into the endosperm, which serves as the embryo's food supply. The ovary will now develop into a fruit and the ovule will develop into a seed.


Fruit and seed

As the development of the embryo and endosperm proceeds within the embryo sac, the sac wall enlarges and combines with the
nucellus In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: the ''integument'', forming its outer layer, the ''nucellus'' (or remnant of the sporangium, megasporangium), ...
(which is likewise enlarging) and the
integument In biology, an integument is the tissue surrounding an organism's body or an organ within, such as skin, a husk, Exoskeleton, shell, germ or Peel (fruit), rind. Etymology The term is derived from ''integumentum'', which is Latin for "a coverin ...
to form the ''seed coat''. The ovary wall develops to form the fruit or
pericarp Fruit anatomy is the plant anatomy of the internal structure of fruit. Fruits are the mature ovary (plants), ovary or ovaries of one or more flowers. They are found in three main anatomical categories: aggregate fruits, multiple fruits, and simp ...
, whose form is closely associated with type of seed dispersal system. Frequently, the influence of fertilisation is felt beyond the ovary, and other parts of the flower take part in the formation of the fruit, e.g., the floral receptacle in the
apple An apple is an edible fruit produced by an apple tree (''Malus domestica''). Apple fruit tree, trees are agriculture, cultivated worldwide and are the most widely grown species in the genus ''Malus''. The tree originated in Central Asia, wh ...
,
strawberry The garden strawberry (or simply strawberry; ''Fragaria × ananassa'') is a widely grown Hybrid (biology), hybrid species of the genus ''Fragaria'', collectively known as the strawberries, which are cultivated worldwide for their fruit. The f ...
, and others. The character of the seed coat bears a definite relation to that of the fruit. They protect the embryo and aid in dissemination; they may also directly promote germination. Among plants with indehiscent fruits, in general, the fruit provides protection for the embryo and secures dissemination. In this case, the seed coat is only slightly developed. If the fruit is
dehiscent Dehiscence is the splitting of a mature plant structure along a built-in line of weakness to release its contents. This is common among fruits, anthers and sporangia. Sometimes this involves the complete detachment of a part; structures that op ...
and the seed is exposed, in general, the seed-coat is well developed and must discharge the functions otherwise executed by the fruit. In some cases, like in the Asteraceae family, species have evolved to exhibit heterocarpy, or the production of different fruit morphs.Gardocki, M. E., Zablocki, H., El-Keblawy, A., & Freeman, D. C. (2000). Heterocarpy in Calendula micrantha (Asteraceae): The effects of competition and availability of water on the performance of offspring from different fruit morphs. Evolutionary Ecology Research. 2(6):701-718 These fruit morphs, produced from one plant, are different in size and shape, which influence dispersal range and germination rate. These fruit morphs are adapted to different environments, increasing chances for survival.


Meiosis

Like all diploid
multicellular organism A multicellular organism is an organism that consists of more than one cell (biology), cell, in contrast to unicellular organism. All species of animals, Embryophyte, land plants and most fungi are multicellular, as are many algae, whereas a few ...
s that use
sexual reproduction Sexual reproduction is a type of reproduction that involves a complex Biological life cycle, life cycle in which a gamete (haploid reproductive cells, such as a sperm or egg cell) with a single set of chromosomes combines with another gamete to p ...
, flowering plants generate gametes using a specialised type of cell division called
meiosis Meiosis (; , since it is a reductional division) is a special type of cell division of germ cells in sexually-reproducing organisms that produces the gametes, such as sperm or egg cells. It involves two rounds of division that ultimately ...
. Meiosis takes place in the
ovule In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: the ''integument'', forming its outer layer, the ''nucellus'' (or remnant of the sporangium, megasporangium), ...
—a structure within the ovary that is located within the pistil at the centre of the flower (see diagram labeled "Angiosperm lifecycle"). A diploid cell ( megaspore mother cell) in the ovule undergoes meiosis (involving two successive cell divisions) to produce four cells (megaspores) with haploid nuclei. It is thought that the basal chromosome number in angiosperms is n = 7. One of these four cells (megaspore) then undergoes three successive mitotic divisions to produce an immature embryo sac (megagametophyte) with eight haploid nuclei. Next, these nuclei are segregated into separate cells by cytokinesis to produce three antipodal cells, two synergid cells and an egg cell. Two polar nuclei are left in the central cell of the embryo sac. Pollen is also produced by meiosis in the male anther ( microsporangium). During meiosis, a diploid microspore mother cell undergoes two successive meiotic divisions to produce four haploid cells (microspores or male gametes). Each of these microspores, after further mitoses, becomes a pollen grain (microgametophyte) containing two haploid generative (sperm) cells and a tube nucleus. When a pollen grain makes contact with the female stigma, the pollen grain forms a pollen tube that grows down the style into the ovary. In the act of fertilisation, a male sperm nucleus fuses with the female egg nucleus to form a diploid
zygote A zygote (, ) is a eukaryote, eukaryotic cell (biology), cell formed by a fertilization event between two gametes. The zygote's genome is a combination of the DNA in each gamete, and contains all of the genetic information of a new individual ...
that can then develop into an embryo within the newly forming seed. Upon
germination Germination is the process by which an organism grows from a seed or spore. The term is applied to the sprouting of a seedling from a seed of an flowering plant, angiosperm or gymnosperm, the growth of a sporeling from a spore, such as the spor ...
of the seed, a new plant can grow and mature. The adaptive function of meiosis is currently a matter of debate. A key event during meiosis in a diploid cell is the pairing of
homologous chromosome A couple of homologous chromosomes, or homologs, are a set of one maternal and one paternal chromosome that pair up with each other inside a cell during fertilization. Homologs have the same genes in the same locus (genetics), loci where they pr ...
s and
homologous recombination Homologous recombination is a type of genetic recombination in which genetic information is exchanged between two similar or identical molecules of double-stranded or single-stranded nucleic acids (usually DNA as in Cell (biology), cellular organi ...
(the exchange of genetic information) between homologous chromosomes. This process promotes the production of increased genetic diversity among progeny and the recombinational repair of
damages At common law, damages are a legal remedy, remedy in the form of a money, monetary award to be paid to a claimant as compensation for loss or injury. To warrant the award, the claimant must show that a breach of duty has caused foreseeable loss. ...
in the DNA to be passed on to progeny. To explain the adaptive function of meiosis in flowering plants, some authors emphasise diversity and others emphasise
DNA repair DNA repair is a collection of processes by which a cell (biology), cell identifies and corrects damage to the DNA molecules that encode its genome. In human cells, both normal metabolism, metabolic activities and environmental factors such as r ...
.


Apomixis

Apomixis In botany, apomixis is asexual reproduction without fertilization. Its etymology is Greek for "away from" + "mixing". This definition notably does not mention meiosis. Thus "normal Plant reproduction#Asexual reproduction, asexual reproduction" o ...
(reproduction via asexually formed seeds) is found naturally in about 2.2% of angiosperm genera. One type of apomixis, gametophytic apomixis found in a dandelion species involves formation of an unreduced embryo sac due to incomplete meiosis (apomeiosis) and development of an embryo from the unreduced egg inside the embryo sac, without fertilisation (
parthenogenesis Parthenogenesis (; from the Greek grc, παρθένος, translit=parthénos, lit=virgin, label=none + grc, γένεσις, translit=génesis, lit=creation, label=none) is a natural form of asexual reproduction in which growth and development ...
). Some angiosperms, including many citrus varieties, are able to produce fruits through a type of apomixis called
nucellar embryony Nucellar embryony (notated Nu+) is a form of seed A seed is an Plant embryogenesis, embryonic plant enclosed in a testa (botany), protective outer covering, along with a food reserve. The formation of the seed is a part of the process of re ...
.


Uses

Agriculture Agriculture or farming is the practice of cultivating Plant, plants and livestock. Agriculture was the key development in the rise of Sedentism, sedentary human civilization, whereby farming of Domestication, domesticated species created food ...
is almost entirely dependent on angiosperms, which provide virtually all plant-based food, and also provide a significant amount of
livestock Livestock are the domesticated animals raised in an agricultural setting to provide labor and produce diversified products for consumption such as meat, eggs, milk, fur, leather, and wool Wool is the textile fibre obtained from sheep an ...
feed. Of all the families of plants, the
Poaceae Poaceae () or Gramineae () is a large and nearly ubiquitous Family (biology), family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species culti ...
, or grass family (providing grains), is by far the most important, providing the bulk of all feedstocks (
rice Rice is the seed of the Poaceae, grass species ''Oryza sativa'' (Asian rice) or less commonly ''Oryza glaberrima'' (African rice). The name wild rice is usually used for species of the genera ''Zizania (genus), Zizania'' and ''Porteresia'', bo ...
,
maize Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American English, North American and Australian English), is a cereal grain first domesticated by indigenous peoples of Mexico, indigenous ...
,
wheat Wheat is a Poaceae, grass widely Agriculture, cultivated for its seed, a cereal grain that is a worldwide staple food. The Taxonomy of wheat, many species of wheat together make up the genus ''Triticum'' ; the most widely grown is common wheat ...
,
barley Barley (''Hordeum vulgare''), a member of the grass family, is a major cereal grain grown in temperate climates globally. It was one of the first cultivated grains, particularly in Eurasia Eurasia (, ) is the largest continental area o ...
, rye, oats,
pearl millet Pearl millet (''Cenchrus americanus'', commonly known as the synonym ''Pennisetum glaucum''; also known as 'Bajra' in Hindi language, Hindi, 'Sajje' in Kannada, 'Kambu' in Tamil language, Tamil, 'Bajeer' in Kumaoni language, Kumaoni and 'Maiwa' ...
,
sugar cane Sugarcane or sugar cane is a species of (often hybrid) tall, Perennial plant, perennial grass (in the genus ''Saccharum'', tribe Andropogoneae) that is used for sugar Sugar industry, production. The plants are 2–6 m (6–20 ft) tall with ...
,
sorghum ''Sorghum'' () is a genus of about 25 species of flowering plants in the grass family (Poaceae). Some of these species are grown as cereals for human consumption and some in pastures for animals. One species is grown for grain, while many other ...
). The
Fabaceae The Fabaceae or Leguminosae,International Code of Nomenc ...
, or legume family, comes in second place. Also of high importance are the
Solanaceae The Solanaceae , or nightshades, are a family (biology), family of flowering plants that ranges from Annual plant, annual and perennial herbs to vines, lianas, epiphytes, shrubs, and trees, and includes a number of agricultural crops, medicinal ...
, or nightshade family (
potato The potato is a starch#Food, starchy food, a tuber of the plant ''Solanum tuberosum'' and is a root vegetable native to the Americas. The plant is a perennial plant, perennial in the nightshade family Solanaceae. Wild potato species can be fo ...
es,
tomato The tomato is the edible Berry (botany), berry of the plant ''Solanum lycopersicum'', commonly known as the tomato plant. The species originated in western South America, Mexico, and Central America. The Mexican Nahuatl word gave rise to th ...
es, and peppers, among others); the
Cucurbitaceae The Cucurbitaceae, also called cucurbits or the gourd family, are a plant family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or ...
, or
gourd Gourds include the fruits of some flowering plant species in the family Cucurbitaceae, particularly ''Cucurbita'' and ''Lagenaria''. The term refers to a number of species and subspecies, many with hard shells, and some without. One of the earli ...
family (including
pumpkin A pumpkin is a vernacular term for mature winter squash of species and varieties in the genus ''Cucurbita'' that has culinary and cultural significance but no agreed upon botanical or scientific meaning. The term ''pumpkin'' is sometimes use ...
s and
melon A melon is any of various plants of the family Cucurbitaceae with sweet, edible, and fleshy fruit. The word "melon" can refer to either the plant or specifically to the fruit. Botanically, a melon is a kind of botanical berry, berry, specifical ...
s); the
Brassicaceae Brassicaceae () or (the older) Cruciferae () is a medium-sized and economically important Family (biology), family of flowering plants commonly known as the mustards, the crucifers, or the cabbage family. Most are herbaceous plants, while some ar ...
, or
mustard plant The mustard plant is any one of several plant species in the genera ''Brassica'' and ''Sinapis'' in the family Brassicaceae (the mustard family). Mustard seed is used as a spice. Grinding and mixing the seeds with water, vinegar, or other liqui ...
family (including
rapeseed Rapeseed (''Brassica napus ''subsp.'' napus''), also known as rape, or oilseed rape, is a bright-yellow flowering member of the family Brassicaceae (mustard or cabbage family), cultivated mainly for its oil-rich seed, which naturally contains a ...
and the innumerable varieties of the
cabbage Cabbage, comprising several cultivars of ''Brassica oleracea'', is a leafy green, red (purple), or white (pale green) biennial plant grown as an Annual plant, annual vegetable crop for its dense-leaved heads. It is descended from the wild cabb ...
species ''
Brassica oleracea ''Brassica oleracea'' is a plant species from family Brassicaceae that includes many common cultivars used as vegetables, such as cabbage, broccoli, cauliflower, kale, Brussels sprouts, collard greens, Savoy cabbage, kohlrabi, and gai lan. Its u ...
''); and the
Apiaceae Apiaceae or Umbelliferae is a family of mostly aromatic flowering plants named after the type genus ''Apium'' and commonly known as the celery, carrot or parsley family, or simply as umbellifers. It is the 16th-largest family of flowering plants ...
, or
parsley Parsley, or garden parsley (''Petroselinum crispum'') is a species of flowering plant in the family Apiaceae that is native to the central and eastern Mediterranean region (Sardinia, Lebanon, Israel, Cyprus, Turkey, southern Italy, Greece, Por ...
family. Many of our fruits come from the
Rutaceae The Rutaceae is a family (biology), family, commonly known as the rueRUTACEAE
in BoDD ...
, or rue family (including
oranges An orange is a fruit In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering. Fruits are the means by which flowering plants (also known as angiosperms) disseminate their see ...
,
lemon The lemon (''Citrus limon'') is a species of small evergreen trees in the flowering plant family Rutaceae, native to Asia, primarily Northeast India (Assam), Northern Myanmar or China. The tree's ellipsoidal yellow hesperidium, fruit is us ...
s,
grapefruit The grapefruit (''Citrus'' × ''paradisi'') is a subtropical citrus tree known for its relatively large, Taste#Sourness, sour to semi-sweet, somewhat Taste#Bitterness, bitter fruit. The interior flesh is segmented and varies in color from pale y ...
s, etc.), and the
Rosaceae Rosaceae (), the rose family, is a medium-sized family (biology), family of flowering plants that includes 4,828 known species in 91 genera. The name is derived from the type genus ''Rose, Rosa''. Among the most species-rich genera are ''Alche ...
, or rose family (including
apple An apple is an edible fruit produced by an apple tree (''Malus domestica''). Apple fruit tree, trees are agriculture, cultivated worldwide and are the most widely grown species in the genus ''Malus''. The tree originated in Central Asia, wh ...
s,
pear Pears are fruits produced and consumed around the world, growing on a tree and harvested in the Northern Hemisphere in late summer into October. The pear tree and shrub are a species of genus ''Pyrus'' , in the Family (biology), family Rosacea ...
s,
cherries A cherry is the fruit of many plants of the genus ''Prunus'', and is a fleshy drupe (stone fruit). Commercial cherries are obtained from cultivars of several species, such as the sweet ''Prunus avium'' and the sour ''Prunus cerasus''. The nam ...
,
apricot An apricot (, ) is a fruit, or the tree that bears the fruit, of several species in the genus ''Prunus''. Usually, an apricot is from the species ''Prunus armeniaca, P. armeniaca'', but the fruits of the other species in ''Prunus'' sect. ''Arm ...
s,
plum A plum is a fruit of some species in Prunus subg. Prunus, ''Prunus'' subg. ''Prunus'.'' Dried plums are called prunes. History Plums may have been one of the first fruits domesticated by humans. Three of the most abundantly cultivated spe ...
s, etc.). In some parts of the world, certain single species assume paramount importance because of their variety of uses, for example the coconut (''
Cocos nucifera The coconut tree (''Cocos nucifera'') is a member of the palm tree The Arecaceae is a family (biology), family of Perennial plant, perennial flowering plants in the Monocotyledon, monocot order (biology), order Arecales. Their growth ...
'') on Pacific
atoll An atoll () is a ring-shaped island, including a coral rim that encircles a lagoon partially or completely. There may be coral islands or cays on the rim. Atolls are located in warm Tropics, tropical or Subtropics, subtropical oceans and seas ...
s, and the olive (''
Olea europaea The olive, botanical name ''Olea europaea'', meaning 'European olive' in Latin, is a species of small tree or shrub in the family (biology), family Oleaceae, found traditionally in the Mediterranean Basin. When in shrub form, it is known as '' ...
'') in the
Mediterranean region In biogeography, the Mediterranean Basin (; also known as the Mediterranean Region or sometimes Mediterranea) is the region of lands around the Mediterranean Sea that have mostly a Mediterranean climate, with mild to cool, rainy winters and wa ...
. Flowering plants also provide economic resources in the form of
wood Wood is a porous and fibrous structural tissue found in the Plant stem, stems and roots of trees and other woody plants. It is an organic materiala natural composite material, composite of cellulose fibers that are strong in tension and emb ...
,
paper Paper is a thin sheet material produced by mechanically or chemically processing cellulose fibres derived from wood, Textile, rags, poaceae, grasses or other vegetable sources in water, draining the water through fine mesh leaving the fibre e ...
, fiber (
cotton Cotton is a soft, fluffy Staple (textiles), staple fiber that grows in a wikt:boll, boll, or protective case, around the seeds of the cotton plants of the genus ''Gossypium'' in the mallow family Malvaceae. The fiber is almost pure cellulose ...
,
flax Flax, also known as common flax or linseed, is a flowering plant, ''Linum usitatissimum'', in the family Linaceae. It is cultivated as a food and fiber crop in regions of the world with temperate climates. Textiles made from flax are known in W ...
, and
hemp Hemp, or industrial hemp, is a botanical class of ''Cannabis sativa'' cultivars grown specifically for industrial or medicinal use. It can be used to make a wide range of products. Along with bamboo, hemp is among the fastest growing plants o ...
, among others), medicines (
digitalis ''Digitalis'' ( or ) is a genus of about 20 species of herbaceous plant, herbaceous perennial plants, shrubs, and Biennial plant, biennials, commonly called foxgloves. ''Digitalis'' is native to Europe, western Asia, and northwestern Afric ...
,
camphor Camphor () is a waxy, colorless solid with a strong aroma. It is classified as a terpenoid and a cyclic ketone. It is found in the wood of the camphor laurel (''Cinnamomum camphora''), a large evergreen tree found in East Asia; and in the kap ...
), decorative and landscaping plants, and many other uses.
Coffee Coffee is a drink prepared from roasted coffee beans. Darkly colored, bitter, and slightly acidic, coffee has a stimulant, stimulating effect on humans, primarily due to its caffeine content. It is the most popular hot drink in the world. S ...
and cocoa are the common beverages obtained from the flowering plants. The main area in which they are surpassed by other plants—namely, coniferous trees (
Pinales The Order (biology), order Pinales in the Division (biology), division Pinophyta, Class (biology), class Pinophyta, Pinopsida, comprises all the Extant taxon, extant conifers. The distinguishing characteristic is the reproductive structure known ...
), which are non-flowering (gymnosperms)—is
timber Lumber is wood that has been processed into dimensional lumber, including Beam (structure), beams and plank (wood), planks or boards, a stage in the process of wood production. Lumber is mainly used for construction framing, as well as fini ...
and paper production.


See also

* List of garden plants * List of plant orders * List of plants by common name * List of systems of plant taxonomy


Notes


References


Bibliography


Articles, books and chapters

* * * * * *
1st edition published by Oxford University Press in 1991
* * * Cromie, William J. (December 16, 1999)

Harvard University Gazette. * * * * * * * * * * * * * * * * *


Websites

* * *


External links

* * * {{DEFAULTSORT:Flowering Plant Plant sexuality Plants Pollination