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An inflorescence is a group or cluster of
flower A flower, sometimes known as a bloom or blossom Cherry blossoms in Paris in full bloom. In botany, blossoms are the flowers of stone fruit fruit tree, trees (genus ''Prunus'') and of some other plants with a similar appearance that flower prof ...

flower
s arranged on a
stem Stem or STEM may refer to: Biology * Plant stem, the aboveground structures that have vascular tissue and that support leaves and flowers ** Stipe (botany), a stalk that supports some other structure ** Stipe (mycology), the stem supporting the c ...

stem
that is composed of a main
branch A branch ( or , ) or tree branch (sometimes referred to 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 spe ...

branch
or a complicated arrangement of branches. Morphologically, it is the modified part of the
shoot 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 Ancie ...

shoot
of
seed plants The spermatophytes (; ), also known as phanerogams (taxon Phanerogamae) or phaenogams (taxon Phaenogamae), comprise those plants that produce seeds, hence the alternative name seed plants. They are a subset of the embryophytes or land plants. Th ...
where
flower A flower, sometimes known as a bloom or blossom Cherry blossoms in Paris in full bloom. In botany, blossoms are the flowers of stone fruit fruit tree, trees (genus ''Prunus'') and of some other plants with a similar appearance that flower prof ...

flower
s are formed. The modifications can involve the length and the nature of the internodes and the
phyllotaxis 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 Ancie ...
, as well as variations in the proportions, compressions, swellings,
adnation Adnation in Angiosperms is the fusion of two or more whorls A whorl is a type of spiral or circular pattern. Other meanings of whorl include: * Whorl (botany), the attachment of sepals, petals, leaves, or branches at a single point * Whorl (bio ...
s,
connation Connation in plant Plants are mainly multicellular organisms, predominantly photosynthetic Photosynthesis is a process used by plants and other organisms to Energy transformation, convert light energy into chemical energy that, through ...
s and reduction of main and secondary axes. One can also define an inflorescence as the reproductive portion of a plant that bears a cluster of flowers in a specific pattern. The stem holding the whole inflorescence is called a peduncle. The major axis (incorrectly referred to as the main stem) above the peduncle bearing the flowers or secondary branches is called the
rachis feather In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological me ...

rachis
. The stalk of each flower in the inflorescence is called a
pedicel Pedicle or pedicel may refer to: Human anatomy *Pedicle of vertebral arch, the segment between the transverse process and the vertebral body, and is often used as a radiographic marker and entry point in vertebroplasty and kyphoplasty procedures * ...
. A flower that is not part of an inflorescence is called a solitary flower and its stalk is also referred to as a peduncle. Any flower in an inflorescence may be referred to as a floret, especially when the individual flowers are particularly small and borne in a tight cluster, such as in a
pseudanthium A pseudanthium (Greek for "false flower") is 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 (pl ...
. The
fruit 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 ...

fruit
ing stage of an inflorescence is known as an
infructescence Infructescence (fruiting head) is defined as the ensemble of fruits derived from the ovaries of an inflorescence. It usually retains the size and structure of the inflorescence. In some cases, infructescences are similar in appearance to simp ...

infructescence
. Inflorescences may be simple (single) or complex (
panicle A panicle is a much-branched inflorescence. (softcover ). Some authors distinguish it from a compound spike inflorescence, by requiring that the flowers (and fruit) be Pedicel (botany), pedicellate (having a single stem per flower). The branches o ...
). The rachis may be one of several types, including single, composite, umbel, spike or
raceme A raceme ( or ) or racemoid is an unbranched, indeterminate growth, indeterminate type of inflorescence bearing ''pedicellate'' flowers (flowers having short floral stalks called Pedicel (botany), pedicels) along its axis. In botany, an ''axis'' ...

raceme
.


General characteristics

Inflorescences are described by many different characteristics including how the flowers are arranged on the peduncle, the blooming order of the flowers and how different clusters of flowers are grouped within it. These terms are general representations as plants in nature can have a combination of types. These structural types are largely based on natural selection.


Bracts

Inflorescences usually have modified foliage different from the
vegetative
vegetative
part of the plant. Considering the broadest meaning of the term, any leaf associated with an inflorescence is called a
bract ''). All the "leaves" in this image are bracts. 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 th ...

bract
. A bract is usually located at the node where the main stem of the inflorescence forms, joined to the rachis of the plant, but other bracts can exist within the inflorescence itself. They serve a variety of functions which include attracting pollinators and protecting young flowers. According to the presence or absence of bracts and their characteristics we can distinguish: * Ebracteate inflorescences: No bracts in the inflorescence. * Bracteate inflorescences: The bracts in the inflorescence are very specialised, sometimes reduced to small scales, divided or dissected. * Leafy inflorescences: Though often reduced in size, the bracts are unspecialised and look like the typical leaves of the plant, so that the term flowering stem is usually applied instead of inflorescence. This use is not technically correct, as, despite their 'normal' appearance, these ''leaves'' are considered, in fact, ''bracts'', so that 'leafy inflorescence' is preferable. * Leafy-bracted inflorescences: Intermediate between bracteate and leafy inflorescence. If many bracts are present and they are strictly connected to the stem, like in the family
Asteraceae The family In , family (from la, familia) is a of people related either by (by recognized birth) or (by marriage or other relationship). The purpose of families is to maintain the well-being of its members and of society. Ideally, fam ...

Asteraceae
, the bracts might collectively be called an involucre. If the inflorescence has a second unit of bracts further up the stem, they might be called an involucel. Image:Brakteose beblätterung (inflorescence).svg, Ebracteate inflorescence. Image:Wisteria sinensisPNPG.jpg, Ebracteate inflorescence of ''
Wisteria sinensis ''Wisteria sinensis'', commonly known as the Chinese wisteria, is a species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A speci ...

Wisteria sinensis
'' Image:Brakteose_beblätterung_2_(inflorescence).svg, Bracteate inflorescence. Image:Pedicularis verticillata a3.jpg, Bracteate inflorescence of ''
Pedicularis verticillata ''Pedicularis verticillata'', the whorled lousewort, is a species of flowering plant in the family Orobanchaceae which can be found in Alaska, North-Western Canada, and everywhere in China at the elevation of . Description The plant is perennial ...

Pedicularis verticillata
''. Image:Frondobrakteose Beblätterung (inflorescence).svg, Leafy-bracted inflorescence. Image:Rhinanthus angustifolius.jpg, Leafy-bracted inflorescence of ''
Rhinanthus angustifolius ''Rhinanthus angustifolius'', the narrow-leaved rattle or greater yellow-rattle, is a plant species of the genus ''Rhinanthus''. It is an annual plant, annual wildflower native plant, native to temperate grasslands in much of Europe, and north and ...

Rhinanthus angustifolius
''. Image:Frondose beblätterung (inflorescence).svg, Leafy inflorescence. Image:Unknown plant 01 bgiu.jpg, Leafy inflorescence of ''
Aristolochia clematitis ''Aristolochia clematitis'', the (European) birthwort, is a twining herbaceous plant in the family Aristolochiaceae, which is native to Europe. The leaves are heart shaped and the flowers are pale yellow and tubular in form. The plant seeks light ...

Aristolochia clematitis
''.


Terminal flower

Plant organs can grow according to two different schemes, namely
monopodial Vascular plants with monopodial growth habits grow upward from a single point. They add leaves to the apex each year and the stem grows longer accordingly. The word ''Monopodial'' is derived from Greek "mono-", ''one'' and "podial", "foot", in refer ...
or
racemose A raceme ( or ) or racemoid is an unbranched, indeterminate growth, indeterminate type of inflorescence bearing ''pedicellate'' flowers (flowers having short floral stalks called Pedicel (botany), pedicels) along its axis. In botany, an ''axis'' ...
and
sympodial Sympodial growth is type of bifurcating branching pattern where one branch develops more strongly than the other, resulting in the stronger branches forming the primary shoot and the weaker branches appearing laterally. A sympodium, also referred ...
or cymose. In inflorescences these two different growth patterns are called indeterminate and determinate respectively, and indicate whether a terminal flower is formed and where flowering starts within the inflorescence. * Indeterminate inflorescence:
Monopodial Vascular plants with monopodial growth habits grow upward from a single point. They add leaves to the apex each year and the stem grows longer accordingly. The word ''Monopodial'' is derived from Greek "mono-", ''one'' and "podial", "foot", in refer ...
(racemose) growth. The terminal bud keeps growing and forming lateral flowers. A terminal flower is never formed. * Determinate inflorescence:
Sympodial Sympodial growth is type of bifurcating branching pattern where one branch develops more strongly than the other, resulting in the stronger branches forming the primary shoot and the weaker branches appearing laterally. A sympodium, also referred ...
(cymose) growth. The terminal bud forms a terminal flower and then dies out. Other flowers then grow from lateral buds. Indeterminate and determinate inflorescences are sometimes referred to as open and closed inflorescences respectively. The indeterminate patterning of flowers is derived from determinate flowers. It is suggested that indeterminate flowers have a common mechanism that prevents terminal flower growth. Based on phylogenetic analyses, this mechanism arose independently multiple times in different species. In an indeterminate inflorescence there is no true terminal flower and the stem usually has a rudimentary end. In many cases the last true flower formed by the terminal bud (subterminal flower) straightens up, appearing to be a terminal flower. Often a vestige of the terminal bud may be noticed higher on the stem. Image:Offener_Blütenstand_(inflorescence).svg, Indeterminate inflorescence with a perfect acropetal maturation. Image:Offener_Blütenstand_(inflorescence)_m_K.svg, Indeterminate inflorescence with an acropetal maturation and lateral flower buds. Image:Pseudoterminalbluete (inflorescence).svg, Indeterminate inflorescence with the subterminal flower to simulate the terminal one (vestige present) In determinate inflorescences the terminal flower is usually the first to mature (precursive development), while the others tend to mature starting from the bottom of the stem. This pattern is called acropetal maturation. When flowers start to mature from the top of the stem, maturation is basipetal, while when the central mature first, divergent. Image:Akropetale Effloration (inflorescence).svg, Determinate inflorescence with acropetal maturation Image:Basipetale effloration (inflorescence).svg, Determinate inflorescence with basipetal maturation Image:Divergente effloration (inflorescence).svg, Determinate inflorescence with divergent maturation


Phyllotaxis

As with
leaves A leaf (plural leaves) is the principal lateral appendage of the vascular plant plant stem, stem, usually borne above ground and specialized for photosynthesis. The leaves, stem, flower and fruit together form the shoot system. Leaves are ...

leaves
, flowers can be arranged on the stem according to many different patterns. See '
Phyllotaxis 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 Ancie ...
' for in-depth descriptions Image:Inflorescences Raceme Kwiatostan Grono.svg, Alternate flowers Image:Traube dekussiert (inflorescence).svg, Opposite flowers Similarly arrangement of leaf in bud is called Ptyxis. When a single or a cluster of flower(s) is located at the axil of a bract, the location of the bract in relation to the stem holding the flower(s) is indicated by the use of different terms and may be a useful diagnostic indicator. Typical placement of bracts include: * Some plants have bracts that subtend the inflorescence, where the flowers are on branched stalks; the bracts are not connected to the stalks holding the flowers, but are adnate or attached to the main stem (Adnate describes the fusing together of different unrelated parts. When the parts fused together are the same, they are connately joined.) * Other plants have the bracts subtend the
pedicel Pedicle or pedicel may refer to: Human anatomy *Pedicle of vertebral arch, the segment between the transverse process and the vertebral body, and is often used as a radiographic marker and entry point in vertebroplasty and kyphoplasty procedures * ...
or peduncle of single flowers. Metatopic placement of bracts include: * When the bract is attached to the stem holding the flower (the pedicel or peduncle), it is said to be recaulescent; sometimes these bracts or bracteoles are highly modified and appear to be appendages of the flower calyx. Recaulescences is the fusion of the subtending leaf with the stem holding the bud or the bud itself, thus the leaf or bract is adnate to the stem of flower. * When the formation of the bud is shifted up the stem distinctly above the subtending leaf, it is described as concaulescent. Image:Bluete und Tragblatt (inflorescence).svg, Flower and subtending bract Image:Türkenbund dunkel.jpg, '''' (flower and subtending bract) Image:Konkauleszenz (inflorescence).svg, Concaulescence Image:Tomato scanned.jpg, '''' (concaulescence) Image:Rekauleszenz (inflorescence).svg, Recaulescence Image:Tilia cordata Owoce lipy 656.jpg, ''
Tilia cordata ''Tilia cordata'', the small-leaved lime or small-leaved linden, is a species of '' Tilia'' native to much of Europe. Other common names include little-leaf or littleleaf linden or small-leaved linden or traditionally in South East England, pry or ...

Tilia cordata
'' (recaulescence)


Organization

There is no general consensus in defining the different inflorescences. The following is based on Focko Weberling's ''Morphologie der Blüten und der Blütenstände'' (Stuttgart, 1981). The main groups of inflorescences are distinguished by branching. Within these groups, the most important characteristics are the intersection of the axes and different variations of the model. They may contain many flowers (pluriflor) or a few (pauciflor). Inflorescences can be simple or compound.


Simple inflorescences


Indeterminate or racemose

Indeterminate simple inflorescences are generally called racemose . The main kind of racemose inflorescence is the raceme (, from classical Latin ''racemus'', cluster of grapes). The other kind of racemose inflorescences can all be derived from this one by dilation, compression, swelling or reduction of the different axes. Some passage forms between the obvious ones are commonly admitted. * A
raceme A raceme ( or ) or racemoid is an unbranched, indeterminate growth, indeterminate type of inflorescence bearing ''pedicellate'' flowers (flowers having short floral stalks called Pedicel (botany), pedicels) along its axis. In botany, an ''axis'' ...

raceme
is an unbranched, indeterminate inflorescence with pedicellate (having short floral stalks) flowers along the axis. * A
spike Spike, spikes, or spiking may refer to: Arts, entertainment, and media Books * The Spike (novel), ''The Spike'' (novel), a novel by Arnaud de Borchgrave * The Spike (book), ''The Spike'' (book), a nonfiction book by Damien Broderick * ''The Spike ...

spike
is a type of raceme with flowers that do not have a pedicel. * A racemose
corymb Corymb is a botanical Botany, also called , plant biology or phytology, is the science Science (from the Latin word ''scientia'', meaning "knowledge") is a systematic enterprise that Scientific method, builds and Taxonomy (general), o ...
is an unbranched, indeterminate inflorescence that is flat-topped or convex due to their outer pedicels which are progressively longer than inner ones. * An
umbel 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 Ancien ...
is a type of raceme with a short axis and multiple floral pedicels of equal length that appear to arise from a common point. It is characteristic of
Umbelliferae 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, ...
. * A spadix is a spike of flowers densely arranged around it, enclosed or accompanied by a highly specialised bract called a
spathe In , a bract is a modified or specialized , especially one associated with a reproductive structure such as a , axis or . Bracts are often (but not always) different from foliage leaves. They may be smaller, larger, or of a different color, shape ...
. It is characteristic of the family
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. The spadix (botany), spadix is usually accompanied by, and sometimes partially enclosed in, a ...

Araceae
. * A
flower head A pseudanthium (Greek for "false flower") is an inflorescence that resembles a flower. The word is sometimes used for other structures that are neither a true flower nor a true inflorescence. Examples of pseudanthia include flower head, composite ...
or capitulum is a very contracted raceme in which the single sessile flowers share are borne on an enlarged stem. It is characteristic of
Dipsacaceae The Dipsacaceae have been recognized as a family (the teasel family) of the order Dipsacales containing 350 species of perennial or biennial herb In general use, herbs are plants with savory or aromatic properties that are used for flavoring an ...
. * A
catkin A catkin or ament is a slim, cylindrical flower A flower, sometimes known as a bloom or blossom, is the reproduction, reproductive structure found in flowering plants (plants of the division Magnoliophyta, also called angiosperms). The biologica ...

catkin
or ament is a scaly, generally drooping spike or raceme. Cymose or other complex inflorescences that are superficially similar are also generally called thus. Image:Traube (inflorescence).svg,
Raceme A raceme ( or ) or racemoid is an unbranched, indeterminate growth, indeterminate type of inflorescence bearing ''pedicellate'' flowers (flowers having short floral stalks called Pedicel (botany), pedicels) along its axis. In botany, an ''axis'' ...

Raceme
Image:Epilobe feuilles etroites 01.jpg, ''
Epilobium angustifolium ''Chamaenerion angustifolium'' is a perennial herbaceous flowering plant The flowering plants, also known as Angiospermae (), or Magnoliophyta (), are the most diverse group of Embryophyte, land plants, with 64 Order(biology), orders, 416 Fa ...

Epilobium angustifolium
'' Image:Inflorescences Spike Kwiatostan Kłos.svg, Spike Image:Plantagomedia.JPG, ''
Plantago media ''Plantago media'', known as the hoary plantain, is a species of flowering plant Flowering plants include multiple members of the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek#REDIRECT ...

Plantago media
'' (spike) Image:Schirmtraube (inflorescence).svg, Racemose
corymb Corymb is a botanical Botany, also called , plant biology or phytology, is the science Science (from the Latin word ''scientia'', meaning "knowledge") is a systematic enterprise that Scientific method, builds and Taxonomy (general), o ...
Image:Schleifenblume06.jpg, ''
Iberis umbellata ''Iberis umbellata'', common name garden candytuft or globe candytuft, is a herbaceous Herbaceous plants are vascular plants that have no persistent woody stems above ground, including many perennials, and nearly all annuals and biennial Bie ...
'' (racemose corymb) Image:Inflorescences Umbel Kwiatostan Baldach.svg,
Umbel 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 Ancien ...
Image:Astrantia minor.jpg, '''' (umbel) Image:Kolben (inflorescence).svg, Spadix Image:Arum maculatum.jpeg, ''
Arum maculatum ''Arum maculatum'' is a woodland flowering plant species in the family Araceae. It is widespread across most of Europe, as well as Turkey and the Caucasus. It is known by an abundance of common names including snakeshead, adder's root, arum, wild ...

Arum maculatum
'' (spadix) Image:Koepfchen (inflorescence).svg,
Head Head Sport GmbH is an American-Austrian headquartered in . It owns the American tennis racket brand Head. Head GmbH is a group that includes several previously independent companies, including the original "Head Ski Company" (founded in the in ...
(round) Image:Fleur 9 - VTdJ.JPG, ''
Dipsacus fullonum , Ontario , Label_map = yes , image_map = Ontario in Canada 2.svg , map_alt = Map showing Ontario's location east/central of Canada. , coordinates = , capital = Toron ...

Dipsacus fullonum
'' (head) Image:Kaetzchen (inflorescence).svg,
Catkin A catkin or ament is a slim, cylindrical flower A flower, sometimes known as a bloom or blossom, is the reproduction, reproductive structure found in flowering plants (plants of the division Magnoliophyta, also called angiosperms). The biologica ...

Catkin
(racemose or spicate) Image:Alnus incana rugosa catkin.jpg, ''
Alnus incana ''Alnus incana'', the grey alder or speckled alder, is a species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often ...

Alnus incana
'' (ament)


Determinate or cymose

Determinate simple inflorescences are generally called cymose. The main kind of cymose inflorescence is the cyme (pronounced 'saim', from the Latin ''cyma'' in the sense 'cabbage sprout', from Greek ''kuma'' 'anything swollen'). Cymes are further divided according to this scheme: * Only one secondary axis: monochasium ** Secondary buds always develop on the same side of the stem: helicoid cyme or bostryx *** The successive pedicels are aligned on the same plane: drepanium ** Secondary buds develop alternately on the stem : scorpioid cyme *** The successive pedicels are arranged in a sort of spiral: cincinnus (characteristic of the
Boraginaceae Boraginaceae, the Borago, borage or forget-me-not family, includes about 2,000 species of shrubs, trees and herbs in 146 genus, genera with a worldwide distribution. The APG IV system from 2016 classifies the Boraginaceae as single family of the ...
and
Commelinaceae Commelinaceae is a family In human society, family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of families is to maintain the ...
) *** The successive pedicels follow a zig-zag path on the same plane: rhipidium (many
Iridaceae Iridaceae is a family of plants in order Asparagales Asparagales (asparagoid lilies) is an order (biology), order of plants in modern classification systems such as the Angiosperm Phylogeny Group (APG) and the Angiosperm Phylogeny Web. The ord ...

Iridaceae
) * Two secondary axes: dichasial cyme ** Secondary axis still dichasial: dichasium (characteristic of
Caryophyllaceae Caryophyllaceae, commonly called the pink family or carnation family, is a family In human society, family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other re ...

Caryophyllaceae
) ** Secondary axis monochasia: double scorpioid cyme or double helicoid cyme * More than two secondary axes: pleiochasium File:Monochasium(inflorescence).svg, Monochasium File:Doppelwickel (inflorescence).svg, Double cyme File:Doppelschraubel (inflorescence).svg, Double cyme File:Schroef (bloeiwijze).jpg, Bostryx (lateral and top view) File:Saint John's wort flowers.jpg, ''
Hypericum perforatum ''Hypericum perforatum'', known as perforate St John's-wort, is a flowering plant The flowering plants, also known as Angiospermae (), or Magnoliophyta (), are the most diverse group of Embryophyte, land plants, with 64 Order(biology), orders ...

Hypericum perforatum
'' (bostryx) File:Sikkel (bloeiwijze).jpg, Drepanium (lateral and top view) File:Gladiolus imbricatus a1.jpg, '' Gladiolus imbricatus'' (drepanium) File:Schicht.jpg, Cincinnus (lateral and top view) File:Symphytum officinale 02.jpg, ''
Symphytum officinale ''Symphytum officinale'' is a perennial flowering plant in the family Boraginaceae. Along with thirty four other species of ''Symphytum'', it is known as comfrey. To differentiate it from other members of the genus ''Symphytum'', this species is k ...

Symphytum officinale
'' (cincinnus) File:Waaier (bloeiwijze).jpg, Rhipidium (lateral and top view) File:Canna Endeavour 01.jpg, '' Canna sp.'' (rhipidium) File:Dichasium (inflorescence).svg, Dichasium File:Dichasium (top view) (inflorescence).svg, Dichasium, top view File:2006-10-22Silene dioica07.jpg, ''
Silene dioica ''Silene dioica'' (synonym (taxonomy), syn. ''Melandrium rubrum''), known as red campion and red catchfly, is a herbaceous flowering plant in the family Caryophyllaceae, native throughout central, western and northern Europe, and locally in southe ...

Silene dioica
'' (dichasium)
A cyme can also be so compressed that it looks like an umbel. Strictly speaking this kind of inflorescence could be called umbelliform cyme, although it is normally called simply 'umbel'. Another kind of definite simple inflorescence is the raceme-like cyme or botryoid; that is as a raceme with a terminal flower and is usually improperly called 'raceme'. Image:Inflorescences Umbel Kwiatostan Baldach.svg, Umbelliform cyme Image:Fiore di geranio.JPG, ''
Pelargonium zonale ''Pelargonium zonale'' is a species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group ...

Pelargonium zonale
'' (umbelliform cyme) Image:Botryoid (inflorescence).svg, Botryoid Image:Berberis vernae MS 4426.jpg, ''Berberis vernae'' (botryoid)
A reduced raceme or cyme that grows in the
axil A leaf (plural leaves) is the principal lateral appendage of the vascular plant plant stem, stem, usually borne above ground and specialized for photosynthesis. The leaves and stem together form the shoot. Leaves are collectively referred ...
of a bract is called a fascicle. A verticillaster is a fascicle with the structure of a dichasium; it is common among the
Lamiaceae The Lamiaceae ( ) or Labiatae are a family In human society A society is a Social group, group of individuals involved in persistent Social relation, social interaction, or a large social group sharing the same spatial or social ter ...

Lamiaceae
. Many verticillasters with reduced bracts can form a spicate (spike-like) inflorescence that is commonly called a spike. Image:Gentiana lutea1.JPG, ''
Gentiana lutea ''Gentiana lutea'', the great yellow gentian, is a species of gentian native to the mountain A mountain is an elevated portion of the Earth's crust, generally with steep sides that show significant exposed bedrock. A mountain differs from ...
'' (fascicles) Image:Lamium orvala3.jpg, '''' (verticillaster) Image:Mentha longifolia 2005.08.02 09.53.56.jpg, '''' ('spike')


Compound inflorescences

Simple inflorescences are the basis for compound inflorescences or synflorescences. The single flowers are there replaced by a simple inflorescence, which can be both a racemose or a cymose one. Compound inflorescences are composed of branched stems and can involve complicated arrangements that are difficult to trace back to the main branch. A kind of compound inflorescence is the double inflorescence, in which the basic structure is repeated in the place of single florets. For example, a double raceme is a raceme in which the single flowers are replaced by other simple racemes; the same structure can be repeated to form triple or more complex structures. Compound raceme inflorescences can either end with a final raceme (homoeothetic), or not (heterothetic). A compound raceme is often called a panicle. Note that this definition is very different from that given by Weberling. Compound umbels are umbels in which the single flowers are replaced by many smaller umbels called umbellets. The stem attaching the side umbellets to the main stem is called a ray. Image:Doppeltraube_(inflorescence).svg, Homeothetic compound raceme Image:Melilotus officinalis01.jpg, '''' (homoeothetic compound raceme) Image:Doppeltraube_2_(inflorescence).svg, Heterothetic compound raceme Image:Hebe albicans.jpg, '''' (heterothetic compound raceme) Image:Inflorescences Muktispike Kwiatostan KłosZłożony.svg, Compound spike Image:Lolium multiflorum detail.jpeg, ''
Lolium temulentum ''Lolium temulentum'', typically known as darnel, poison darnel, darnel ryegrass or cockle, is an annual plant of the genus '' Lolium'' within the family Poaceae Poaceae () or Gramineae () is a large and nearly ubiquitous family In huma ...
'' (compound spike) Image:Doppelkoepfchen_(inflorescence).svg, Compound capitulum Image:Echinops Ain France.jpg, ''
Echinops ritro ''Echinops ritro'', the southern globethistle, is a species of flowering plant in the Asteraceae, sunflower family, native plant, native to southern and eastern Europe (from Spain east to Turkey, Ukraine, and Belarus), and western Asia. The speci ...

Echinops ritro
'' (compound capitulum) Image:Inflorescences Umbel Kwiatostan BaldachZłożony.svg, Compound (double) umbel Image:Laserpitium latifolium2.jpg, '' Laserpicium latifolium'' (double umbel) Image:Dreifachdolde_(inflorescence).svg, Compound (triple) umbel
The most common kind of definite compound inflorescence is the panicle (of Webeling, or 'panicle-like cyme'). A panicle is a definite inflorescence that is increasingly more strongly and irregularly branched from the top to the bottom and where each branching has a terminal flower. The so-called cymose corymb is similar to a racemose corymb but has a panicle-like structure. Another type of panicle is the anthela. An anthela is a cymose corymb with the lateral flowers higher than the central ones. Image:Inflorescences Panicle Kwiatostan Wiecha.svg,
Panicle A panicle is a much-branched inflorescence. (softcover ). Some authors distinguish it from a compound spike inflorescence, by requiring that the flowers (and fruit) be Pedicel (botany), pedicellate (having a single stem per flower). The branches o ...
Image:Vigne inflorescence 2.jpg, ''
Vitis vinifera ''Vitis vinifera'', the common grape vine, is a species of flowering plant Flowering plants include multiple members of the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek#REDIRECT Greek ...

Vitis vinifera
'' (panicle) Image:Schirmrispe (inflorescence).svg, Cymose
corymb Corymb is a botanical Botany, also called , plant biology or phytology, is the science Science (from the Latin word ''scientia'', meaning "knowledge") is a systematic enterprise that Scientific method, builds and Taxonomy (general), o ...
Image:Sambucus nigra 003.jpg, ''
Sambucus nigra ''Sambucus nigra'' is a species complex In biology, a species complex is a group of closely related organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any individual contiguous system t ...

Sambucus nigra
'' (cymose corymb) Image:Spirre (inflorescence).svg, Anthela Image:Juncus inflexus.jpeg, '' Juncus inflexus'' (anthela)
A raceme in which the single flowers are replaced by cymes is called a (indefinite) thyrse. The secondary cymes can be of any of the different types of dichasia and monochasia. A botryoid in which the single flowers are replaced by cymes is a definite thyrse or thyrsoid. Thyrses are often confusingly called panicles. Homöokladische Thyrse (inflorescence).svg, Thyrse Aesculus hippocastanum flori.jpg, ''
Aesculus hippocastanum ''Aesculus hippocastanum'', the horse chestnut, is a species of flowering plant The flowering plants, also known as Angiospermae (), or Magnoliophyta (), are the most diverse group of Embryophyte, land plants, with 64 Order(biology), orders, 4 ...

Aesculus hippocastanum
'' Dichasialer zymus (inflorescence).svg, Thyrsoid Syringa11.jpg, ''
Syringa vulgaris ''Syringa vulgaris'', the lilac or common lilac, is a species of flowering plant in the olive family (biology), family Oleaceae, native plant, native to the Balkan Peninsula, where it grows on rocky hills.Rushforth, K. (1999). ''Trees of Britain ...

Syringa vulgaris
''
Other combinations are possible. For example, heads or umbels may be arranged in a corymb or a panicle. Achillea (yarrow) - 16.JPG, ''
Achillea ''Achillea'' is a group of flowering plant The flowering plants, also known as Angiospermae (), or Magnoliophyta (), are the most diverse group of Embryophyte, land plants, with 64 Order(biology), orders, 416 Family (biology), families, appro ...

Achillea
'' sp. (heads in a corymb) Starr 010419-0021 Hedera helix.jpg, ''
Hedera helix ''Hedera helix'', the common ivy, English ivy, European ivy, or just ivy, is a species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversi ...

Hedera helix
'' (umbels in a panicle)


Other

The family
Asteraceae The family In , family (from la, familia) is a of people related either by (by recognized birth) or (by marriage or other relationship). The purpose of families is to maintain the well-being of its members and of society. Ideally, fam ...

Asteraceae
is characterised by a highly specialised head technically called a calathid (but usually referred to as 'capitulum' or 'head'). The family
Poaceae Poaceae () or Gramineae () is a large and nearly ubiquitous family In , family (from la, familia) is a of people related either by (by recognized birth) or (by marriage or other relationship). The purpose of families is to maintain ...
has a peculiar inflorescence of small spikes (
spikelet A spikelet, in botany, describes the typical arrangement of the flowers of Poaceae, grasses, Cyperaceae, sedges and some other Monocots. Each spikelet has one or more florets. The spikelets are further grouped into Raceme, panicles or spikes. The ...
s) organised in panicles or spikes that are usually simply and improperly referred to as spike and panicle. The genus ''
Ficus ''Ficus'' ( or ) is a genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology Biology is the natural science that studies life and living organisms, including ...

Ficus
'' (
Moraceae The Moraceae — often called the mulberry family or fig family — are a family of flowering plant The flowering plants, also known as Angiospermae (), or Magnoliophyta (), are the most diverse group of Embryophyte, land plants, with 64 Order( ...

Moraceae
) has an inflorescence called
syconium Syconium (plural = syconia) is the type of inflorescence An inflorescence is a group or cluster of s arranged on a that is composed of a main or a complicated arrangement of branches. , it is the modified part of the of where s are forme ...
and the genus ''
Euphorbia ''Euphorbia'' is a very large and diverse genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV ...

Euphorbia
'' has cyathia (sing. ''cyathium''), usually organised in umbels. Chamomile@original size.jpg, ''
Matricaria chamomilla ''Matricaria chamomilla'' (synonym: ''Matricaria recutita''), commonly known as chamomile (also spelled camomile), German chamomile, Hungarian chamomile (kamilla), wild chamomile, blue chamomile, scented mayweed, is an annual plant 240px, Pea ...

Matricaria chamomilla
'' (calathid) Wheat close-up.JPG, ''
Triticum aestivum Common wheat (''Triticum aestivum''), also known as bread wheat, is a cultivated wheat species. About 95% of wheat produced worldwide is common wheat; it is the most widely grown of all crops and the cereal with the highest monetary yield. Nom ...

Triticum aestivum
'' (compound spikes, "spikes") Lemont rice.jpg, ''
Oryza sativa ''Oryza sativa'', common name, commonly known as Asian rice, is the plant species most commonly referred to in English as rice. It is the List of rice cultivars, type of farmed rice whose cultivars are most common globally, and History of rice cu ...

Oryza sativa
'' (spikes in a panicle, "panicle") Some figs.jpg, ''
Ficus carica ''Ficus carica'' is an Asian species of flowering plant The flowering plants, also known as Angiospermae (), or Magnoliophyta (), are the most diverse group of Embryophyte, land plants, with 64 Order(biology), orders, 416 Family (biology), fami ...

Ficus carica
'' (syconium) Euphorbia tridentata ies.jpg, '' Euphorbia tridentata'' (cyathium) Euphorbia cyparissias 02 bgiu.jpg, '''' (cyathia in an umbel) Coleus inflorescence.JPG, ''
Coleus ''Coleus'' is a genus of annual or perennial herbs or shrubs, sometimes succulent, sometimes with a fleshy or tuberous rootstock, found in the Old World tropics and subtropics. The relationship among the genera ''Coleus'', ''Solenostemon'' and ' ...

Coleus
'' (false spike)
Some species have inflorescences reduced to composite flowers or pseudanthia, in which case it is difficult to differentiate between inflorescences and single flowers.


Development and patterning


Development


Genetic basis

Genes that shape inflorescence development have been studied at great length in ''
Arabidopsis ''Arabidopsis'' (rockcress) is a genus in the family Brassicaceae Brassicaceae () or Cruciferae () is a medium-sized and economically important Family (biology), family of flowering plants commonly known as the mustards, the crucifers, or the c ...

Arabidopsis
''. ''LEAFY'' (LFY) is a gene that promotes floral meristem identity, regulating inflorescence development in ''Arabidopsis.'' Any alterations in timing of LFY expression can cause formation of different inflorescences in the plant. Genes similar in function to LFY include ''APETALA1'' (AP1). Mutations in LFY, AP1, and similar promoting genes can cause conversion of flowers into shoots. In contrast to LEAFY, genes like ''terminal flower'' (TFL) support the activity of an inhibitor that prevents flowers from growing on the inflorescence apex (flower primordium initiation), maintaining inflorescence meristem identity. Both types of genes help shape flower development in accordance with the
ABC model of flower development The ABC model of flower development is a scientific model Scientific modelling is a scientific activity, the aim of which is to make a particular part or feature of the world easier to understand, define, quantify, visualize, or simulate ...
. Studies have been recently conducted or are ongoing for homologs of these genes in other flower species.


Environmental influences

Inflorescence-feeding insect herbivores shape inflorescences by reducing lifetime fitness (how much flowering occurs), seed production by the inflorescences, and plant density, among other traits. In the absence of this herbivory, inflorescences usually produce more flower heads and seeds. Temperature can also variably shape inflorescence development. High temperatures can impair the proper development of flower buds or delay bud development in certain species, while in others, an increase in temperature can hasten inflorescence development.


Meristems and inflorescence architecture

The shift from the vegetative to reproductive phase of a flower involves the development of an inflorescence meristem that generates floral meristems. Plant inflorescence architecture depends on which meristems becomes flowers and which become shoots. Consequently, genes that regulate floral meristem identity play major roles in determining inflorescence architecture because their expression domain will direct where the plant's flowers are formed. On a larger scale, inflorescence architecture affects quality and quantity of offspring from selfing and outcrossing, as the architecture can influence pollination success. For example, ''
Asclepias ''Asclepias'' is a genus of herbaceous, perennial plant, perennial, flowering plants known as milkweeds, named for their latex, a milky substance containing cardiac glycosides termed cardenolides, exuded where cells are damaged. Most species are ...

Asclepias
'' inflorescences have been shown to have an upper size limit, shaped by self-pollination levels due to crosses between inflorescences on the same plant or between flowers on the same inflorescence. In '' Aesculus sylvatica'', it has been shown that the most common inflorescence sizes are correlated with the highest fruit production as well.


References


Bibliography

* Focko Weberling: ''Morphologie der Blüten und der Blütenstände; Zweiter Teil''. Verlag Eugen Ulmer, Stuttgart 1981 * Wilhelm Troll: ''Die Infloreszenzen; Erster Band''. Gustav Fischer Verlag, Stuttgart 1964 * Wilhelm Troll: ''Die Infloreszenzen; Zweiter Band, Erster Teil''. Gustav Fischer Verlag, Stuttgart 1969 * Wilhelm Troll: ''Praktische Einführung in die Pflanzenmorphologie''. Gustav Fischer Verlag, Jena 1957 * Bernhard Kausmann: ''Pflanzenanatomie''. Gustav Fischer Verlag, Jena 1963 * Walter S. Judd, Christopher S. Campbell, Elizabeth A. Kellogg, Peter F. Stevens, Michael J. Donoghue: ''Plant Systematics: A Phylogenetic Approach'', Sinauer Associates Inc. 2007 * Stevens, P. F. (2001 onwards). Angiosperm Phylogeny Website

Version 7, May 2006 nd more or less continuously updated since * Strasburger, Noll, Schenck, Schimper: Lehrbuch der Botanik für Hochschulen. 4. Auflage, Gustav Fischer, Jena 1900, p. 459
R J Ferry. Inflorescences and Their Names. The McAllen International Orchid Society Journal.Vol. 12(6), pp. 4-11 June 2011


External links

* {{Authority control Inflorescence
Plant morphology ''Plant morphology'' is the field in botany that studies the diversity in forms, with the naked eye or slight optical magnification. This is opposed to plant anatomy (see :Plant anatomy) that needs to cut into plants to be able to study its subject, ...