GROUPS (APG IV)
* Angiospermae Lindl.
* Magnoliophyta Cronquist ,
Takht. they are distinguished from
gymnosperms by characteristics including flowers , endosperm within
the seeds, and the production of fruits that contain the seeds.
Etymologically, angiosperm means a plant that produces seeds within an
enclosure, in other words, a fruiting plant. The term "angiosperm"
comes from the Greek composite word (angeion, "case" or "casing", and
sperma, "seed") meaning "enclosed seeds", after the enclosed condition
of the seeds.
The ancestors of flowering plants diverged from gymnosperms in the
Triassic Period , during the range 245 to 202 million years ago (mya),
and the first flowering plants are known from 160 mya. They
diversified extensively during the Lower
Cretaceous , became
widespread by 120 mya, and replaced conifers as the dominant trees
from 100 to 60 mya.
* 1 Description
* 1.1 Angiosperm derived characteristics
* 1.2 Vascular anatomy
* 1.3 Reproductive anatomy
* 2 Taxonomy
* 2.1 History of classification
* 2.2 Modern classification
Flowering plant diversity
* 4 Ecology
Fertilization and embryogenesis
Fruit and seed
* 5 Uses
* 6 See also
* 7 Notes
* 8 References
* 9 Bibliography
* 9.1 Articles, books and chapters
* 9.2 Websites
* 10 External links
ANGIOSPERM DERIVED CHARACTERISTICS
Bud of a pink rose
Angiosperms differ from other seed plants in several ways, described
in the table. These distinguishing characteristics taken together have
made the angiosperms the most diverse and numerous land plants and the
most commercially important group to humans.
Distinctive features of
Flowers, the reproductive organs of flowering plants, are the most
remarkable feature distinguishing them from the other seed plants.
Flowers provided angiosperms with the means to have a more
species-specific breeding system, and hence a way to evolve more
readily into different species without the risk of crossing back with
related species. Faster speciation enabled the
Angiosperms to adapt to
a wider range of ecological niches . This has allowed flowering plants
to largely dominate terrestrial ecosystems.
Stamens with two pairs of pollen sacs
Stamens are much lighter than the corresponding organs of
gymnosperms and have contributed to the diversification of angiosperms
through time with adaptations to specialized pollination syndromes,
such as particular pollinators. Stamens have also become modified
through time to prevent self-fertilization , which has permitted
further diversification, allowing angiosperms eventually to fill more
Reduced male parts, three cells
The male gametophyte in angiosperms is significantly reduced in
size compared to those of gymnosperm seed plants. The smaller size of
the pollen reduces the amount of time between pollination — the
pollen grain reaching the female plant — and fertilization . In
gymnosperms, fertilization can occur up to a year after pollination,
whereas in angiosperms, fertilization begins very soon after
pollination. The shorter amount of time between pollination and
fertilization allows angiosperms to produce seeds earlier after
pollination than gymnosperms, providing angiosperms a distinct
Closed carpel enclosing the ovules (carpel or carpels and accessory
parts may become the fruit )
The closed carpel of angiosperms also allows adaptations to
specialized pollination syndromes and controls. This helps to prevent
self-fertilization, thereby maintaining increased diversity. Once the
ovary is fertilized, the carpel and some surrounding tissues develop
into a fruit. This fruit often serves as an attractant to
seed-dispersing animals. The resulting cooperative relationship
presents another advantage to angiosperms in the process of dispersal
Reduced female gametophyte, seven cells with eight nuclei
The reduced female gametophyte, like the reduced male gametophyte,
may be an adaptation allowing for more rapid seed set, eventually
leading to such flowering plant adaptations as annual herbaceous
life-cycles, allowing the flowering plants to fill even more niches.
In general, endosperm formation begins after fertilization and
before the first division of the zygote .
Endosperm is a highly
nutritive tissue that can provide food for the developing embryo , the
cotyledons , and sometimes the seedling when it first appears.
Cross-section of a stem of the angiosperm flax :
Pith , 2.
Protoxylem , 3.
Xylem I, 4.
Phloem I, 5. Sclerenchyma
(bast fibre ), 6. Cortex , 7. Epidermis
The amount and complexity of tissue-formation in flowering plants
exceeds that of gymnosperms. The vascular bundles of the stem are
arranged such that the xylem and phloem form concentric rings.
In the dicotyledons, 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
or active formative tissue known as cambium . By the formation of a
layer of cambium 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
of growth, called annual rings .
Among the monocotyledons, 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
Plant reproductive morphology
Plant reproductive morphology A
collection of flowers forming an inflorescence
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 of the ovule and development of fruit containing seeds .
The floral apparatus may arise terminally on a shoot or from the axil
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
There are two kinds of reproductive cells produced by flowers.
Microspores, which will divide to become pollen grains , are the
"male" cells and are borne in the stamens (or microsporophylls). The
"female" cells called megaspores, which will divide to become the egg
cell (megagametogenesis ), are contained in the ovule and enclosed in
the carpel (or megasporophyll).
The flower may consist only of these parts, as in willow , where each
flower comprises only a few stamens or two carpels. Usually, other
structures are present and serve to protect the sporophylls and to
form an envelope attractive to pollinators. The individual members of
these surrounding structures are known as sepals and petals (or tepals
in flowers such as
Magnolia 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 or bird pollinators.
Attraction is effected by color, scent , and nectar , which may be
secreted in some part of the flower. The characteristics that attract
pollinators account for the popularity of flowers and flowering plants
While the majority of flowers are perfect or hermaphrodite (having
both pollen and ovule producing parts in the same flower structure),
flowering plants have developed numerous morphological and
physiological mechanisms to reduce or prevent self-fertilization.
Heteromorphic flowers have short carpels and long stamens, or vice
versa, so animal pollinators cannot easily transfer pollen to the
pistil (receptive part of the carpel). Homomorphic flowers may employ
a biochemical (physiological) mechanism called self-incompatibility to
discriminate between self and non-self pollen grains. In other
species, the male and female parts are morphologically separated,
developing on different flowers.
HISTORY OF CLASSIFICATION
From 1736, an illustration of Linnaean classification
The botanical term "Angiosperm", from the Ancient Greek
αγγείον, angeíon (bottle, vessel) and σπέρμα, (seed),
was coined in the form Angiospermae by
Paul Hermann in 1690, as the
name of one of his primary divisions of the plant kingdom . This
included flowering plants possessing seeds enclosed in capsules,
distinguished from his Gymnospermae, or 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 term and its antonym were
Carl Linnaeus with the same sense, but with restricted
application, in the names of the orders of his class Didynamia . Its
use with any approach to its modern scope became possible only after
1827, when Robert Brown established the existence of truly naked
ovules in the Cycadeae and Coniferae , and applied to them the name
Gymnosperms. From that time onward, as long as these
as was usual, reckoned as dicotyledonous flowering plants, the term
Angiosperm was used antithetically by botanical writers, with varying
scope, as a group-name for other dicotyledonous plants. An
auxanometer , a device for measuring increase or rate of growth in
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
Anthophyta ("flowering plants") a second choice.
These names are not linked to any rank. The
Wettstein system and the
Engler system use the name Angiospermae, at the assigned rank of
Reveal system treated flowering plants as subdivision
Magnoliophytina (Frohne ">
Monocot (left) and dicot seedlings
Traditionally, the flowering plants are divided into two groups,
which in the
Cronquist system are called
Magnoliopsida (at the rank
of class, formed from the family name Magnoliaceae) and
the rank of class, formed from the family name
Liliaceae ). Other
descriptive names allowed by Article 16 of the
Dicotyledones or Dicotyledoneae, and
Monocotyledoneae, which have a long history of use. In English a
member of either group may be called a dicotyledon (plural
dicotyledons) and monocotyledon (plural monocotyledons), or
abbreviated, as dicot (plural dicots) and monocot (plural monocots).
These names derive from the observation that the dicots most often
have two cotyledons , 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 group (clade ) but that the dicots do not (they are
paraphyletic ). Nevertheless, the majority of dicot species do form a
monophyletic group, called the eudicots or tricolpates . Of the
remaining dicot species, most belong to a third major clade known as
the magnoliids , containing about 9,000 species. The rest include a
paraphyletic grouping of early branching taxa known collectively as
the basal angiosperms , plus the families
There are eight groups of living angiosperms:
Basal angiosperms (ANA: Amborella, Nymphaeales, Austrobaileyales)
Amborella , a single species of shrub from
New Caledonia ;
Nymphaeales , about 80 species, water lilies and
Austrobaileyales , about 100 species of woody plants from various
parts of the world
Core angiosperms (
Chloranthales , several dozen species of aromatic plants with
Magnoliids , about 9,000 species, characterized by trimerous
flowers, pollen with one pore, and usually branching-veined
leaves—for example magnolias , bay laurel , and black pepper ;
Monocots , about 70,000 species, characterized by trimerous
flowers, a single cotyledon , pollen with one pore, and usually
parallel-veined leaves—for example grasses , orchids , and palms ;
Ceratophyllum , about 6 species of aquatic plants , perhaps most
familiar as aquarium plants;
Eudicots , about 175,000 species, characterized by 4- or 5-merous
flowers, pollen with three pores, and usually branching-veined
leaves—for example sunflowers , petunia , buttercup , apples , and
The exact relationship between these eight groups is not yet clear,
although there is agreement that the first three groups to diverge
from the ancestral angiosperm were
Nymphaeales , and
Austrobaileyales . The term basal angiosperms refers to these three
groups. Among the remaining five groups (core angiosperms), the
relationship between the three broadest of these groups (magnoliids,
monocots, and eudicots) remains unclear. Zeng and colleagues (Fig. 1)
describe four competing schemes. Of these, 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 2016 Angiosperm Phylogeny
Group revision (APG IV) retained the overall higher order relationship
described in APG III.
Phylogeny of the flowering plants, as of
APG III (2009).
2. Example of alternative phylogeny (2010)
basal angiosperms core angiosperms
3. APG IV (2016)
DETAILED CLADOGRAM OF THE ANGIOSPERM PHYLOGENY GROUP (APG) IV
Amborellales Melikyan, Bobrov border-left:1px
Nymphaeales Salisbury ex von Berchtold border-left:1px
Takhtajan ex Reveal 1992
Chloranthales Mart. 1835
Canellales Cronquist 1957
Piperales von Berchtold vertical-align:top;text-align:center;">
Magnoliales de Jussieu ex von Berchtold border-left:1px
Laurales de Jussieu ex von Berchtold
Acorales Link 1835
Alismatales Brown ex von Berchtold border-left:1px
Dioscoreales Brown 1835
Pandanales Brown ex von Berchtold
Liliales Perleb 1826
Asparagales Link 1829
Arecales Bromhead 1840
Poales Small 1903
Zingiberales Grisebach 1854
Commelinales de Mirbel ex von Berchtold
Ceratophyllales Link 1829
Ranunculales de Jussieu ex von Berchtold border-left:1px
Proteales de Jussieu ex von Berchtold border-left:1px
Takhtajan ex Cronquist 1981
Takhtajan ex Reveal 1996
Takhtajan ex Reveal 1992
Dilleniales de Candolle ex von Berchtold border-left:1px
Saxifragales von Berchtold border-left:1px
Vitales de Jussieu ex von Berchtold border-left:1px
Zygophyllales Link 1829
Celastrales Link 1829
Oxalidales von Berchtold border-left:1px
Malpighiales de Jussieu ex von Berchtold
Fabales Bromhead 1838
Rosales von Berchtold border-left:1px
Cucurbitales de Jussieu ex von Berchtold border-left:1px
Fagales Engler 1892
Geraniales de Jussieu ex von Berchtold border-left:1px
Myrtales de Jussieu ex von Berchtold
Takhtajan ex Reveal 1993
Picramniales Doweld 2001
Sapindales de Jussieu ex von Berchtold border-left:1px
Huerteales Doweld 2001
Malvales de Jussieu ex von Berchtold border-left:1px
Brassicales Bromhead 1838
Berberidopsidales Doweld 2001
Santalales Brown ex von Berchtold border-left:1px
Cornales Link 1829
Ericales von Berchtold border-left:1px
Icacinales Van Tieghem 1900
Garryales Mart. 1835
Gentianales de Jussieu ex von Berchtold border-left:1px
Solanales de Jussieu ex von Berchtold border-left:1px
Boraginales de Jussieu ex von Berchtold border-left:1px
Vahliales Doweld 2001
Lamiales Bromhead 1838
Aquifoliales Senft 1856
Escalloniales Mart. 1835
Asterales Link 1829
Bruniales Dumortier 1829
Apiales Nakai 1930
Takhtajan ex Reveal 1992
Dipsacales de Jussieu ex von Berchtold
Evolutionary history of plants
Evolutionary history of plants § Flowers
Fossilized spores suggest that higher plants (embryophytes ) have
lived on land 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 meiosporangia for dispersal by spores 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 , the spike-moss. The result for the
ancestors of angiosperms was enclosing them in a case, the seed . The
first seed bearing plants, like the ginkgo , and conifers (such as
pines and firs ), did not produce flowers. The pollen grains (male
Ginkgo and cycads produce a pair of flagellated,
mobile sperm cells that "swim" down the developing pollen tube to the
female and her eggs. Flowers of
Malus sylvestris (crab apple)
Flowers and leaves of
Oxalis pes-caprae (Bermuda buttercup)
The apparently sudden appearance of nearly modern flowers in the
fossil record initially posed such a problem for the theory of
Charles Darwin called it an "abominable mystery".
However, the fossil record has considerably grown since the time of
Darwin, and recently discovered angiosperm fossils such as
Archaefructus , along with further discoveries of fossil gymnosperms,
suggest how angiosperm characteristics may have been acquired in a
series of steps. Several groups of extinct gymnosperms, in particular
seed ferns , have been proposed as the ancestors of flowering plants,
but there is no continuous fossil evidence showing exactly how flowers
evolved. Some older fossils, such as the upper
Triassic Sanmiguelia ,
have been suggested. Based on current evidence, some propose 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
Ma) suggests an older date for their origin. 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 other gymnosperms .
The evolution of seed plants and later angiosperms appears to be the
result of two distinct rounds of whole genome duplication events.
These occurred at 319 million years ago and 192 million years ago .
Another possible whole genome duplication event at 160 million years
ago 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 , and directly
addresses Darwin's "abominable mystery."
The earliest known macrofossil confidently identified as an
Archaefructus liaoningensis , is dated to about 125
million years BP (the
Cretaceous period), whereas pollen considered
to be of angiosperm origin takes the fossil record back to about 130
million years BP. However, one study has suggested that the
Schmeissneria , traditionally considered a
type of ginkgo , may be the earliest known angiosperm, or at least a
close relative. In addition, circumstantial chemical evidence has
been found for the existence of angiosperms as early as 250 million
Oleanane , a secondary metabolite produced by many
flowering plants, has been found in
Permian 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
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.
DNA analysis based on molecular systematics showed that
Amborella trichopoda , found on the Pacific island of
New Caledonia ,
belongs to a sister group of the other flowering plants, and
morphological studies suggest that it has features that may have been
characteristic of the earliest flowering plants.
Nymphaeales , and
as separate lineages from the remaining angiosperm clade at a very
early stage in flowering plant evolution.
The great angiosperm radiation , when a great diversity of
angiosperms appears in the fossil record, occurred in the
Cretaceous (approximately 100 million years ago). However, a study
in 2007 estimated that the division of the five most recent (the genus
Ceratophyllum , the family
Chloranthaceae , the eudicots , the
magnoliids , and the monocots ) of the eight main groups occurred
around 140 million years ago. By the late Cretaceous, angiosperms
appear to have dominated environments formerly occupied by ferns and
cycadophytes , but large canopy-forming trees replaced conifers as the
dominant trees only close to the end of the
Cretaceous 66 million
years ago or even later, at the beginning of the
Tertiary . The
radiation of herbaceous angiosperms occurred much later. Yet, many
fossil plants recognizable as belonging to modern families (including
beech , oak , maple , and magnolia ) had already appeared by the late
Cretaceous . Two bees on a flower head of Creeping Thistle,
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 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 or island chain, where the plants
bearing them were able to develop a highly specialized relationship
with some specific animal (a wasp , for example). Such a relationship,
with a hypothetical wasp carrying pollen from one plant to another
much the way fig wasps do today, could result in the development of a
high degree of specialization in both the plant(s) and their partners.
Note that the wasp example is not incidental; bees , 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 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 uses a combination of genes 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 (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 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 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 dinosaurs, with their eating habits,
provided a selective pressure on plants, for which adaptations either
succeeded in deterring or coping with predation by herbivores.
FLOWERING PLANT DIVERSITY
A poster of twelve different species of flowers of the
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 or 11,000 species of pteridophytes , showing that the
flowering plants are much more diverse. The number of families in APG
(1998) was 462. In
APG II (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
(2009) there are 415 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 5 clades contain a little over 250 species
in total; i.e. less than 0.1% of flowering plant diversity, divided
among 9 families. The 42 most-diverse of 443 families of flowering
plants by species, in their APG circumscriptions, are
Asteraceae or Compositae (daisy family): 22,750 species;
Orchidaceae (orchid family): 21,950;
Fabaceae or Leguminosae (bean family): 19,400;
Rubiaceae (madder family): 13,150;
Poaceae or Gramineae (grass family): 10,035;
Lamiaceae or Labiatae (mint family): 7,175;
Euphorbiaceae (spurge family): 5,735;
Melastomataceae or Melastomaceae (melastome family): 5,005;
Myrtaceae (myrtle family): 4,625;
Apocynaceae (dogbane family): 4,555;
Cyperaceae (sedge family): 4,350;
Malvaceae (mallow family): 4,225;
Araceae (arum family): 4,025;
Ericaceae (heath family): 3,995;
Gesneriaceae (gesneriad family): 3,870;
Apiaceae or Umbelliferae (parsley family): 3,780;
Brassicaceae or Cruciferae (cabbage family): 3,710:
Piperaceae (pepper family): 3,600;
Acanthaceae (acanthus family): 3,500;
Rosaceae (rose family): 2,830;
Boraginaceae (borage family): 2,740;
Urticaceae (nettle family): 2,625;
Ranunculaceae (buttercup family): 2,525;
Lauraceae (laurel family): 2,500;
Solanaceae (nightshade family): 2,460;
Campanulaceae (bellflower family): 2,380;
Arecaceae (palm family): 2,361;
Annonaceae (custard apple family): 2,220;
Caryophyllaceae (pink family): 2,200;
Orobanchaceae (broomrape family): 2,060;
Amaranthaceae (amaranth family): 2,050;
Iridaceae (iris family): 2,025;
Aizoaceae or Ficoidaceae (ice plant family): 2,020;
Rutaceae (rue family): 1,815;
Phyllanthaceae (phyllanthus family): 1,745;
Scrophulariaceae (figwort family): 1,700;
Gentianaceae (gentian family): 1,650;
Convolvulaceae (bindweed family): 1,600;
Proteaceae (protea family): 1,600;
Sapindaceae (soapberry family): 1,580;
Cactaceae (cactus family): 1,500;
Aralia or ivy family): 1,450.
Of these, the Orchidaceae, Poaceae, Cyperaceae, Arecaceae, and
Iridaceae are monocot families; Piperaceae, Lauraceae, and Annonaceae
are magnoliid dicots; the rest of the families are eudicots.
FERTILIZATION AND EMBRYOGENESIS
Plant embryogenesis Angiosperm
Double fertilization refers to a process in which two sperm cells
fertilize cells in the ovary . This process begins when a pollen grain
adheres to the stigma of the pistil (female reproductive structure),
germinates, and grows a long pollen tube . 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 fertilize the egg cell, producing a diploid
(2n) zygote. The second sperm cell fuses with both central cell
nuclei, producing a triploid (3n) 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
Fruit The fruit of the
Horse Chestnut tree
As the development of embryo and endosperm proceeds within the embryo
sac, the sac wall enlarges and combines with the nucellus (which is
likewise enlarging) and the integument to form the seed coat. The
ovary wall develops to form the fruit or pericarp , whose form is
closely associated with the manner of distribution of the seed.
Frequently, the influence of fertilization 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 , strawberry , 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 and the seed is exposed, in
general, the seed-coat is well developed, and must discharge the
functions otherwise executed by the fruit.
Flowering plants generate gametes using a specialized cell division
called meiosis .
Meiosis takes place in the ovule (a structure within
the ovary that is located within the pistil at the center 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 or female
gametes) with haploid nuclei. One of these four cells (megaspore)
then undergoes three successive mitotic divisions to produce an
immature embryo sac (megagametocyte) with eight haploid nuclei. Next,
these nuclei are segregated into separate cells by cytokinesis to
producing 3 antipodal cells, 2 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 4 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
fertilization, a male sperm nucleus fuses with the female egg nucleus
to form a diploid zygote that can then develop into an embryo within
the newly forming seed . Upon germination 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 chromosomes and homologous recombination (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 in the
DNA to be passed on
to progeny. To explain the adaptive function of meiosis in flowering
plants, some authors emphasize diversity and others emphasize DNA
Apomixis (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 fertilization (parthenogenesis).
Agriculture is almost entirely dependent on angiosperms, which
provide virtually all plant-based food, and also provide a significant
amount of livestock feed. Of all the families of plants, the
or grass family (grains), is by far the most important, providing the
bulk of all feedstocks (rice , corn — maize , wheat , barley , rye ,
oats , pearl millet , sugar cane , sorghum ). The
Fabaceae , or legume
family, comes in second place. Also of high importance are the
Solanaceae , or nightshade family (potatoes , tomatoes , and peppers ,
among others), the
Cucurbitaceae , or gourd family (also including
pumpkins and melons ), the
Brassicaceae , or mustard plant family
(including rapeseed and the innumerable varieties of the cabbage
Brassica oleracea ), and the
Apiaceae , or parsley family.
Many of our fruits come from the
Rutaceae , or rue family (including
oranges , lemons , grapefruits , etc.), and the
Rosaceae , or rose
family (including apples , pears , cherries , apricots , plums ,
In some parts of the world, certain single species assume paramount
importance because of their variety of uses, for example the coconut
(Cocos nucifera ) on Pacific atolls , and the olive (Olea europaea )
Mediterranean region .
Flowering plants also provide economic resources in the form of wood
, paper , fiber (cotton , flax , and hemp , among others), medicines
(digitalis , camphor ), decorative and landscaping plants, and many
other uses. The main area in which they are surpassed by other plants
— namely, coniferous trees (
Pinales ), which are non-flowering
(gymnosperms ) — is timber and paper production.
* Plants portal
List of garden plants
List of plant orders
List of plants by common name
List of systems of plant taxonomy
* ^ The major exception to the dominance of terrestrial ecosystems
by flowering plants is the coniferous forest .
* ^ A B C APG 2016 .
* ^ Cronquist 1960 .
Takhtajan 1964 .
* ^ Lindley, J (1830). Introduction to the Natural System of
Botany. London: Longman, Rees, Orme, Brown, and Green. xxxvi.
* ^ Cantino, Philip D.; Doyle, James A.; Graham, Sean W.; Judd,
Walter S.; Olmstead, Richard G.; Soltis, Douglas E. ; Soltis, Pamela
S. ; Donoghue, Michael J. (2007). "Towards a phylogenetic nomenclature
of Tracheophyta". Taxon. 56 (3): E1–E44. doi :10.2307/25065865 .
* ^ Cronquist (1988). Magnoliophyta Flowering Plants.
* ^ Christenhusz, M. J. M.; Byng, J. W. (2016). "The number of
known plants species in the world and its annual increase". Phytotaxa.
Magnolia Press. 261 (3): 201–217. doi :10.11646/phytotaxa.261.3.1 .
* ^ Williams, J.H. (2012). "The evolution of pollen germination
timing in flowering plants: Austrobaileya scandens
AoB Plants . 2012
pls010. doi :10.1093/aobpla/pls010 .
* ^ Brown R., Character and description of Kingia, a new genus of
plants found on the southwest coast of New Holland: with observations
on the structure of its unimpregnated ovulum; and on the female flower
of Cycadeae and Coniferae, in: King P.P.(Ed.) Narrative of a Survey of
the Intertropical and western coasts of Australia, performed between
years 1818 and 1822. John Murray, London, 1827, vol. 2., pp.
* ^ A B C APG 2003 .
* ^ A B C D E APG 2009 .
* ^ A B Chase & Reveal 2009 .
* ^ "As easy as
APG III - Scientists revise the system of
classifying flowering plants". The Linnean Society of London.
2009-10-08. Retrieved 2009-10-02.
* ^ A B C D E F Jeffrey D. Palmer; Douglas E. Soltis; Mark W. Chase
(2004). "The plant tree of life: an overview and some points of view".
American Journal of Botany. 91 (10): 1437–1445. PMID 21652302 . doi
:10.3732/ajb.91.10.1437 . , Figure 2
* ^ Soltis & Soltis 2004 .
* ^ Zeng et al 2014 .
* ^ A B Bell et al 2010 .
* ^ Edwards, D (2000). "The role of mid-palaeozoic mesofossils in
the detection of early bryophytes" . Philos Trans R Soc Lond B Biol
Sci. 355 (1398): 733–755. PMC 1692787 . PMID 10905607 . doi
* ^ Davies, T. J. (2004). "Darwin\'s abominable mystery: Insights
from a supertree of the angiosperms" . Proceedings of the National
Academy of Sciences. 101 (7): 1904–9. PMC 357025 . PMID 14766971
. doi :10.1073/pnas.0308127100 .
* ^ Hochuli, P. A.; Feist-Burkhardt, S. (2013). "Angiosperm-like
pollen and Afropollis from the Middle
Triassic (Anisian) of the
Germanic Basin (Northern Switzerland)". Front.
Plant Sci. 4: 344. doi
* ^ Jiao, Yuannian; Wickett, No4rman J.; Ayyampalayam, Saravanaraj;
Chanderbali, André S.; et al. (2011). "Ancestral polyploidy in seed
plants and angiosperms". Nature. 473 (7345): 97–100. PMID 21478875 .
doi :10.1038/nature09916 .
* ^ Ewen Callaway (December 2013). "
Shrub genome reveals secrets of
flower power". Nature. doi :10.1038/nature.2013.14426 .
* ^ Keith Adams (December 2013). "Genomic Clues to the Ancestral
Flowering Plant". Science. 342 (6165): 1456–1457. PMID 24357306 .
doi :10.1126/science.1248709 .
* ^ Sun, G.; Ji, Q.; Dilcher, D.L.; Zheng, S.; Nixon, K.C.; Wang,
X. (2002). "Archaefructaceae, a New Basal Angiosperm Family". Science.
296 (5569): 899–904. PMID 11988572 . doi :10.1126/science.1069439 .
* ^ Wing, Xin; Duan, Shuying; Geng, Baoyin; Cui, Jinzhong; Yang,
Yong (2007). "Schmeissneria: A missing link to angiosperms?" . BMC
Evolutionary Biology. 7: 14. PMC 1805421 . PMID 17284326 . doi
* ^ Taylor, David Winship; Li, Hongqi; Dahl, Jeremy; Fago, Fred J.;
Zinniker, David; Moldowan, J. Michael (2006). "Biogeochemical evidence
for the presence of the angiosperm molecular fossil oleanane in
Paleozoic and Mesozoic non-angiospermous fossils". Paleobiology. 32
(2): 179. ISSN 0094-8373 . doi :10.1666/0094-8373(2006)322.0.CO;2 .
* ^ Oily Fossils Provide Clues To The
Evolution Of Flowers —
ScienceDaily (April 5, 2001)
* ^ Poinar Jr., George O; Chambers, Kenton L; Wunderlich, Joerg (10
December 2013). "Micropetasos, a new genus of angiosperms from
Cretaceous Burmese amber" (PDF). J. Bot. Res. Inst. Texas. 7 (2):
745–750. Lay summary (3 January 2014).
* ^ NOVA — Transcripts — First
Flower — PBS Airdate: April
* ^ Soltis, D. E.; Soltis, P. S. (2004). "
Amborella not a "basal
angiosperm"? Not so fast". American Journal of Botany. 91 (6):
997–1001. PMID 21653455 . doi :10.3732/ajb.91.6.997 .
* ^ South Pacific plant may be missing link in evolution of
flowering plants — Public release date: 17 May 2006
* ^ Vialette-Guiraud, AC; Alaux, M; Legeai, F; Finet, C; et al.
(2011). "Cabomba as a model for studies of early angiosperm evolution"
. Annals of Botany. 108 (4): 589–98. PMC 3170152 . PMID 21486926
. doi :10.1093/aob/mcr088 .
* ^ Moore, M. J.; Bell, C. D.; Soltis, P. S. ; Soltis, D. E.
(2007). "Using plastid genome-scale data to resolve enigmatic
relationships among basal angiosperms" . Proceedings of the National
Academy of Sciences. 104 (49): 19363–8. PMC 2148295 . PMID
18048334 . doi :10.1073/pnas.0708072104 .
* ^ David Sadava; H. Craig Heller; Gordon H. Orians; William K.
Purves; David M. Hillis (December 2006). Life: the science of biology.
Macmillan. pp. 477–. ISBN 978-0-7167-7674-1 . Retrieved 4 August
* ^ Stewart, Wilson Nichols; Rothwell, Gar W. (1993). Paleobotany
and the evolution of plants (2nd ed.). Cambridge Univ. Press. p. 498.
ISBN 0-521-23315-1 .
* ^ Buchmann, Stephen L.; Nabhan, Gary Paul (2012). The Forgotten
Island Press. pp. 41–42. ISBN 978-1-59726-908-7 .
* ^ Age-Old Question On
Evolution Of Flowers Answered —
* ^ Human Affection Altered
Evolution of Flowers — By Robert Roy
Britt, LiveScience Senior Writer (posted: 26 May 2005 06:53 am ET)
* ^ Bakker, Robert T. (17 August 1978). "Dinosaur Feeding Behaviour
and the Origin of Flowering Plants". Nature . London: Macmillan. 274
(5672): 661–663. doi :10.1038/274661a0 .
* ^ Thorne, R. F. (2002). "How many species of seed plants are
there?". Taxon. 51 (3): 511–522.
JSTOR 1554864 . doi
* ^ Scotland, R. W.; Wortley, A. H. (2003). "How many species of
seed plants are there?". Taxon. 52 (1): 101–104.
JSTOR 3647306 . doi
* ^ Govaerts, R. (2003). "How many species of seed plants are
there? – a response". Taxon. 52 (3): 583–584.
JSTOR 3647457 . doi
* ^ Goffinet, Bernard; William R. Buck (2004). "Systematics of the
Bryophyta (Mosses): From molecules to a revised classification".
Monographs in Systematic Botany. Missouri Botanical Garden Press. 98:
* ^ Raven, Peter H., Ray F. Evert, & Susan E. Eichhorn, 2005.
Biology of Plants, 7th edition. (New York: W. H. Freeman and Company).
ISBN 0-7167-1007-2 .
* ^ Frank Harold Trevor Rhodes (1 January 1974). Evolution. Golden
Press. p. 123. ISBN 978-0-307-64360-5 .
* ^ Stevens, P.F. (2011). "Angiosperm
Phylogeny Website (at
Missouri Botanical Garden)".
* ^ "Kew Scientist 30 (October2006)" (PDF).
* ^ Snustad DP, Simmons MJ (2008). Principles of Genetics (5th
ed.). Wiley. ISBN 978-0-470-38825-9 .
* ^ Harrison CJ, Alvey E, Henderson IR (2010). "
flowering plants and other green organisms". J. Exp. Bot. 61 (11):
2863–75. PMID 20576791 . doi :10.1093/jxb/erq191 .
* ^ Mirzaghaderi G, Hörandl E (2016). "The evolution of meiotic
sex and its alternatives" . Proc. Biol. Sci. 283 (1838): 20161221. PMC
5031655 . PMID 27605505 . doi :10.1098/rspb.2016.1221 .
* ^ Hojsgaard D, Klatt S, Baier R, Carman JG, Hörandl E (2014).
"Taxonomy and Biogeography of
Angiosperms and Associated
Biodiversity Characteristics" . CRC Crit Rev
Plant Sci. 33 (5):
414–427. PMC 4786830 . PMID 27019547 . doi
* ^ van Baarlen P, van Dijk PJ, Hoekstra RF, de Jong JH (2000).
"Meiotic recombination in sexual diploid and apomictic triploid
dandelions (Taraxacum officinale L.)". Genome. 43 (5): 827–35. PMID
11081973 . doi :10.1139/gen-43-5-827 .
* ^ Dilcher et al 2016 .
ARTICLES, BOOKS AND CHAPTERS
* APG (2003). "An update of the Angiosperm
classification for the orders and families of flowering plants: APG
Botanical Journal of the Linnean Society . 141 (4): 399–436.
doi :10.1046/j.1095-8339.2003.t01-1-00158.x .
* APG (2009). "An update of the Angiosperm
classification for the orders and families of flowering plants: APG
Botanical Journal of the Linnean Society . 161 (2): 105–121.
doi :10.1111/j.1095-8339.2009.00996.x . Retrieved 2010-12-10.
* APG (2016). "An update of the Angiosperm
classification for the orders and families of flowering plants: APG
Botanical Journal of the Linnean Society . 181 (1): 1–20. doi
:10.1111/boj.12385 . Retrieved 2016-05-20.
* Becker, Kenneth M. (February 1973). "A Comparison of Angiosperm
Classification Systems". Taxon . 22 (1): 19–50. doi :10.2307/1218032
* Bell, Adrian D. (2008) .
Plant Form. An illustrated guide to
flowering plant morphology. Oxford University Press.
* 1st edition ISBN 9780198542193
* Bell, C.D.; Soltis, D.E. ; Soltis, P.S. (2010). "The Age and
Diversification of the
Angiosperms Revisited". American Journal of
Botany . 97 (8): 1296–1303. PMID 21616882 . doi :10.3732/ajb.0900346
* Chase, Mark W. & Reveal, James L. (2009). "A phylogenetic
classification of the land plants to accompany APG III". Botanical
Journal of the Linnean Society. 161 (2): 122–127. doi
* Cromie, William J. (December 16, 1999). "Oldest Known Flowering
Plants Identified By Genes". Harvard University Gazette.
* Cronquist, Arthur (October 1960). "The divisions and classes of
plants". The Botanical Review. 26 (4): 425–482. doi
* Cronquist, Arthur (1981). An Integrated System of Classification
of Flowering Plants. New York: Columbia Univ. Press. ISBN
* Dahlgren, R. M. T. (February 1980). "A revised system of
classification of the angiosperms". Botanical Journal of the Linnean
Society. 80 (2): 91–124. doi :10.1111/j.1095-8339.1980.tb01661.x .
* Dahlgren, Rolf (February 1983). "General aspects of angiosperm
evolution and macrosystematics". Nordic Journal of Botany. 3 (1):
119–149. doi :10.1111/j.1756-1051.1983.tb01448.x .
* Dilcher, D. (2000). "Toward a new synthesis: Major evolutionary
trends in the angiosperm fossil record". Proceedings of the National
Academy of Sciences. 97 (13):