Editing Inflorescence

{{short description|Botanical term for a cluster of flowers}}
{{Distinguish|Fluorescence}}
{{Redirect|Inflorescent|the album|Inflorescent (album){{!}}''Inflorescent'' (album)}}
{{more citations needed|date=November 2023}}
[[File:Aloe hereroensis Auob C15.JPG|thumb|''[[Aloe hereroensis]]'', showing inflorescence with branched [[Peduncle (botany)|peduncle]]]]
[[File:Amorphophallus at Fairchild.jpg|thumb|''[[Amorphophallus titanum]]'' has the world's largest unbranched inflorescence. Photo of the plant in bloom in 2000 at [[Fairchild Tropical Botanic Garden]] in [[Miami]], Florida, US]]

In [[botany]], an '''inflorescence''' is a group or cluster of [[flower]]s arranged on a [[plant]]'s [[Plant stem|stem]] that is composed of a main [[branch]] or a system of branches.<ref>Guertin, P., Barnett, L., Denny, E.G., Schaffer, S.N. 2015. USA National Phenology Network Botany Primer. USA-NPN Education and Engagement Series 2015-001. [https://Www.usanpn.org www.usanpn.org].</ref> An inflorescence is categorized on the basis of the arrangement of flowers on a main axis ([[Peduncle (botany)|peduncle]]) and by the timing of its flowering (determinate and indeterminate).<ref>{{Cite web |date=2023-09-26 |title=Inflorescence {{!}} Racemes, Spikes & Cymes {{!}} Britannica |url=https://www.britannica.com/science/inflorescence |access-date=2023-11-03 |website=www.britannica.com |language=en}}</ref>

[[Morphology (biology)|Morphologically]], an inflorescence is the modified part of the [[Shoot (botany)|shoot]] of [[spermatophyte|seed plants]] where flowers are formed on the axis of a plant. The modifications can involve the length and the nature of the [[internode (botany)|internode]]s and the [[phyllotaxis]], as well as variations in the proportions, compressions, swellings, [[adnation]]s, [[connation]]s and reduction of main and secondary axes.{{Citation needed|date=November 2023}}

One can also define an inflorescence as the reproductive portion of a plant that bears a cluster of flowers in a specific pattern.{{Citation needed|date=November 2023}}

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==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. Because flowers facilitate [[plant reproduction]], inflorescence characteristics are largely a result of [[natural selection]].<ref>{{Cite journal|last1=Kirchoff|first1=Bruce K.|last2=Claßen-Bockhoff|first2=Regine|date=2013|title=Inflorescences: concepts, function, development and evolution|journal=Annals of Botany|language=en|volume=112|issue=8|pages=1471–6|doi=10.1093/aob/mct267|pmid=24383103|pmc=3828949}}</ref>

The stem holding the whole inflorescence is called a [[Peduncle (botany)|peduncle]]. The main axis (also referred to as major stem) above the peduncle bearing the flowers or secondary branches is called the [[rachis]].  The stalk of each flower in the inflorescence is called a [[Pedicel (botany)|pedicel]]. 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 [[Glossary of botanical terms|floret]], especially when the individual flowers are particularly small and borne in a tight cluster, such as in a [[pseudanthium]]. The [[fruit]]ing stage of an inflorescence is known as an [[infructescence]]. Inflorescences may be simple (single) or complex ([[panicle]]). The rachis may be one of several types, including single, composite, umbel, spike or [[raceme]]. {{citation needed|date=November 2023}}

In some species the flowers develop directly from the main stem or woody trunk, rather than from the plant's main shoot. This is called [[cauliflory]] and is found across a number of plant families.<ref name="PlantNETC2">{{cite web |title=PlantNET - NSW Flora Online - Glossary |url=http://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&glossary=yes&alpha=C |accessdate=May 17, 2022}}</ref> An extreme version of this is [[Cauliflory|flagelliflory]] where long, whip-like branches grow from the main trunk to the ground and even below it. Inflorescences form directly on these branches.<ref name="Fernanda Martínez-Velarde_et_al20232">{{cite journal |last1=Fernanda Martínez-Velarde |first1=Maria |last2=6 others |first2=and |date=2023 |title=Desmopsisterriflora, an extraordinary new species of Annonaceae with flagelliflory |journal=PhytoKeys |issue=227 |pages=181–198 |doi=10.3897/phytokeys.227.102279 |pmc=10314296 |pmid=37396012 |doi-access=free|bibcode=2023PhytK.227..181M }}</ref>

===Terminal flower===
Plant organs can grow according to two different schemes, namely [[monopodial]] or '''[[racemose]]''' and [[sympodial]] or '''cymose'''. In inflorescences these two different growth patterns are called [[Indeterminate growth|indeterminate]] and determinate respectively, and indicate whether a terminal flower is formed and where flowering starts within the inflorescence.
* '''Indeterminate inflorescence''': [[Monopodial]] (racemose) growth. The terminal bud keeps growing and forming lateral flowers. A terminal flower is never formed.
* '''Determinate inflorescence''': [[Sympodial]] (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.<ref name=":32">{{Cite journal|last1=Bradley|first1=Desmond|last2=Ratcliffe|first2=Oliver|last3=Vincent|first3=Coral|last4=Carpenter|first4=Rosemary|author-link4=Rosemary Carpenter|last5=Coen|first5=Enrico|date=1997-01-03|title=Inflorescence Commitment and Architecture in Arabidopsis|journal=Science|language=en|volume=275|issue=5296|pages=80–83|doi=10.1126/science.275.5296.80|issn=0036-8075|pmid=8974397|s2cid=20301629}}</ref>

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.

<gallery>
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)
</gallery>

In '''determinate inflorescences''' the terminal flower is usually the first to mature (precursive development), while the others tend to mature starting from the base of the stem. This pattern is called '''acropetal''' maturation. When flowers start to mature from the top of the stem, maturation is '''basipetal''', whereas when the central mature first, maturation is '''divergent'''.

<gallery>
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
</gallery>

===Phyllotaxis===
As with [[leaf|leaves]], flowers can be arranged on the stem according to many different patterns. See '[[Phyllotaxis]]' for in-depth descriptions.

<gallery>
Image:Inflorescences Raceme Kwiatostan Grono.svg|Alternate flowers
Image:Traube dekussiert (inflorescence).svg|Opposite flowers
</gallery>
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 [[adnation|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 (botany)|pedicel]] 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,<ref>Kubitzki, Klaus, and Clemens Bayer. 2002. ''Flowering plants, Dicotyledons: Malvales, Capparales, and non-betalain Caryophyllales. The Families and genera of vascular plants, 5.'' Berlin: Springer. p. 77</ref> 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'''.
<gallery>
Image:Bluete und Tragblatt (inflorescence).svg|Flower and subtending bract
Image:Türkenbund dunkel.jpg|''[[Lilium martagon]]'' (flower and subtending bract)
Image:Konkauleszenz (inflorescence).svg|Concaulescence
Image:Tomato scanned.jpg|''[[Tomato|Solanum lycopersicum]]'' (concaulescence)
Image:Rekauleszenz (inflorescence).svg|Recaulescence
Image:Tilia cordata Owoce lipy 656.jpg|''[[Tilia cordata]]'' (recaulescence)
</gallery>

==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===
[[File:Sunflower macro wide.jpg|thumb|Inflorescence of sessile disc florets forming the [[Head (botany)|capitulum]]]]

====Indeterminate or racemose====
Indeterminate simple inflorescences are generally called '''racemose''' {{IPAc-en|ˈ|r|æ|s|ᵻ|m|oʊ|s}}. The main kind of racemose inflorescence is the '''raceme''' ({{IPAc-en|ˈ|r|æ|s|iː|m}}, from classical Latin ''racemus'', [[cluster of grapes]]).<ref>Oxford English Dictionary. Raceme 2. Bot. A type of inflorescence in which the flowers are arranged on short, nearly equal, lateral pedicels, at equal distances along a single elongated axis</ref> 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]]''' is an unbranched, [[indeterminate growth|indeterminate]] inflorescence with pedicellate (having short floral stalks) flowers along the axis.
* A '''[[raceme|spike]]''' is a type of raceme with flowers that do not have a pedicel.
* A racemose '''[[corymb]]''' 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]]''' 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]].
* A '''[[spadix (botany)|spadix]]''' is a spike of flowers densely arranged around it, enclosed or accompanied by a highly specialised bract called a '''[[spadix (botany)|spathe]]'''. It is characteristic of the family [[Araceae]].
* A '''[[Pseudanthium|flower head]]''' 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]].
* A '''[[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.

<gallery>
Image:Traube (inflorescence).svg|[[Raceme]]
Image:Epilobe feuilles etroites 01.jpg|''[[Epilobium angustifolium]]''
Image:Inflorescences Spike Kwiatostan Kłos.svg|Spike
Image:Plantagomedia.JPG|''[[Plantago media]]'' (spike)
Image:Schirmtraube (inflorescence).svg| Racemose [[corymb]]
Image:Schleifenblume06.jpg|''[[Iberis umbellata]]'' (racemose corymb)
Image:Inflorescences Umbel Kwiatostan Baldach.svg|[[Umbel]]
Image:Astrantia minor.jpg|''[[Astrantia minor]]'' (umbel)
Image:Kolben (inflorescence).svg|[[Spadix (botany)|Spadix]]
Image:Arum maculatum.jpeg|''[[Arum maculatum]]'' (spadix)
Image:Koepfchen (inflorescence).svg|[[Pseudanthium|Head]] (round)
Image:Fleur 9 - VTdJ.JPG|''[[Dipsacus fullonum]]'' (head)
Image:Kaetzchen (inflorescence).svg|[[Catkin]] (racemose or spicate)
Image:Alnus incana rugosa catkin.jpg|''[[Alnus incana]]'' (ament)
</gallery>

====Determinate or cymose====
{{Anchor|cyme|cymose}}
Determinate simple inflorescences are generally called '''cymose'''. The main kind of cymose inflorescence is the '''cyme''' (pronounced {{IPAc-en|s|aɪ|m}}), from the Latin ''cyma'' in the sense 'cabbage sprout', from Greek ''kuma'' 'anything swollen').<ref>Collins English Dictionary. 8th Edition first published in 2006</ref><ref>Oxford English Dictionary. Cyme(1) Bot. A species of inflorescence wherein the primary axis bears a single terminal flower which develops first, the system being continued by axes of secondary and higher orders which develop successively in like manner; a centrifugal or definite
inflorescence: opposed to [[Raceme]]. Applied esp. to compound inflorescences of this type forming a more or less flat head.</ref> 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]] and [[Commelinaceae]])
*** The successive pedicels follow a zig-zag path on the same plane: '''rhipidium''' (many [[Iridaceae]])
* Two secondary axes: '''dichasial cyme'''
** Secondary axis still dichasial: '''dichasium''' (characteristic of [[Caryophyllaceae]])
** Secondary axis monochasia: '''double scorpioid cyme''' or '''double helicoid cyme'''
* More than two secondary axes: '''pleiochasium'''

<gallery>
File:Monochasium(inflorescence).svg|Simple dichasium
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]]'' (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]]'' (cincinnus)
File:Waaier (bloeiwijze).jpg|Rhipidium (lateral and top view)
File:Canna Endeavour 01.jpg|''[[Canna (plant)|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]]'' (dichasium)
</gallery>

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'.

<gallery>
Image:Inflorescences Umbel Kwiatostan Baldach.svg|Umbelliform cyme
Image:Fiore di geranio.JPG|''[[Pelargonium zonale]]'' (umbelliform cyme)
Image:Botryoid (inflorescence).svg|Botryoid
Image:Berberis vernae MS 4426.jpg|''Berberis vernae'' (botryoid)
</gallery>

A reduced raceme or cyme that grows in the [[axil]] of a bract is called a '''fascicle'''. A '''verticillaster''' is a fascicle with the structure of a dichasium; it is common among the [[Lamiaceae]]. Many verticillasters with reduced bracts can form a spicate (spike-like) inflorescence that is commonly called a '''spike'''.

<gallery>
Image:Gentiana lutea1.JPG|''[[Gentiana lutea]]'' (fascicles)
Image:Lamium orvala3.jpg|''[[Lamium orvala]]'' (verticillaster)
Image:Mentha longifolia 2005.08.02 09.53.56.jpg|''[[Mentha longifolia]]'' ('spike')
</gallery>

===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'''. This definition is very different from that given by [[Focko Weberling|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'''.

<gallery>
Image:Doppeltraube_(inflorescence).svg|Homeothetic compound raceme
Image:Melilotus officinalis01.jpg|''[[Melilotus officinalis]]'' (homoeothetic compound raceme)
Image:Doppeltraube_2_(inflorescence).svg|Heterothetic compound raceme
Image:Hebe albicans.jpg|''[[Veronica albicans]]'' (heterothetic compound raceme)
Image:Inflorescences Muktispike Kwiatostan KłosZłożony.svg|Compound spike
Image:Lolium multiflorum detail.jpeg|''[[Lolium temulentum]]'' (compound spike)
Image:Doppelkoepfchen_(inflorescence).svg|Compound capitulum
Image:Echinops Ain France.jpg|''[[Echinops ritro]]'' (compound capitulum)
Image:Inflorescences Umbel Kwiatostan BaldachZłożony.svg|Compound (double) umbel
Image:Laserpitium latifolium2.jpg|''[[Laserpitium latifolium]]'' (double umbel)
Image:Dreifachdolde_(inflorescence).svg|Compound (triple) umbel
</gallery>

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.

<gallery>
Image:Inflorescences Panicle Kwiatostan Wiecha.svg|[[Panicle]]
Image:Vigne inflorescence 2.jpg|''[[Vitis vinifera]]'' (panicle)
Image:Schirmrispe (inflorescence).svg|Cymose [[corymb]]
Image:Sambucus nigra 003.jpg|''[[Sambucus nigra]]'' (cymose corymb)
Image:Spirre (inflorescence).svg|Anthela
Image:Juncus inflexus.jpeg|''[[Juncus inflexus]]'' (anthela)
</gallery>

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'''.

<gallery>
Homöokladische Thyrse (inflorescence).svg|Thyrse
Aesculus hippocastanum flori.jpg|''[[Aesculus hippocastanum]]''
Dichasialer zymus (inflorescence).svg|Thyrsoid
Syringa11.jpg|''[[Syringa vulgaris]]''
</gallery>

Other combinations are possible. For example, heads or umbels may be arranged in a corymb or a panicle.

<gallery>
Achillea (yarrow) - 16.JPG|''[[Achillea]]'' sp. (heads in a corymb)
Starr 010419-0021 Hedera helix.jpg|''[[Hedera helix]]'' (umbels in a panicle)
</gallery>

===Other===
The family [[Asteraceae]] is characterised by a highly specialised head technically called a '''[[calathid]]''' (but usually referred to as 'capitulum' or 'head'). The family [[Poaceae]] has a peculiar inflorescence of small spikes ('''[[spikelet]]s''') organised in panicles or spikes that are usually simply and improperly referred to as '''spike''' and '''panicle'''. The genus ''[[Ficus]]'' ([[Moraceae]]) has an inflorescence called a hypanthodium, which bears numerous flowers on the inside of a convex or involuted compound receptacle.<ref>Simpson, M. G. 2010. ''Plant Systematics'' Burlington: Academic Press. p. 509</ref> The genus ''[[Euphorbia]]'' has '''[[cyathium|cyathia]]''' (sing. ''cyathium''), usually organised in umbels.

<gallery>
Chamomile@original size.jpg|''[[Matricaria chamomilla]]'' (calathid)
Wheat close-up.JPG|''[[Triticum aestivum]]'' (compound spikes, "spikes")
Lemont rice.jpg|''[[Oryza sativa]]'' (spikes in a panicle, "panicle")
Some figs.jpg|''[[Ficus carica]]'' (hypanthodium)
Euphorbia tridentata ies.jpg|''[[Euphorbia tridentata]]'' (cyathium)
Euphorbia cyparissias 02 bgiu.jpg|''[[Euphorbia cyparissias]]'' (cyathia in an umbel)
Coleus inflorescence.JPG|''[[Coleus]]'' (false spike)
</gallery>

Some species have inflorescences reduced to [[Pseudanthium|composite flowers or pseudanthia]], in which case it is difficult to differentiate between inflorescences and single flowers.<ref name=":9">{{Cite journal|last1=Tucker|first1=Shirley C.|last2=Grimes|first2=James|date=1999-10-01|title=The inflorescence: Introduction|journal=The Botanical Review|language=en|volume=65|issue=4|pages=303–316|doi=10.1007/BF02857752|bibcode=1999BotRv..65..303T |s2cid=29599096|issn=0006-8101}}</ref>

== Development and patterning ==

===Development===
====Genetic basis====
Genes that shape inflorescence development have been studied at great length in ''[[Arabidopsis]]''. ''LEAFY'' (LFY) is a gene that promotes [[Meristem|floral meristem]] identity, regulating inflorescence development in ''Arabidopsis.''<ref name=":1">{{Cite journal|last1=Shannon|first1=S.|last2=Meeks-Wagner|first2=D. R.|date=1993-06-01|title=Genetic Interactions That Regulate Inflorescence Development in Arabidopsis.|journal=The Plant Cell|language=en|volume=5|issue=6|pages=639–655|doi=10.1105/tpc.5.6.639|issn=1040-4651|pmid=12271079|pmc=160302}}</ref> Any alterations in timing of LFY expression can cause formation of different inflorescences in the plant.<ref name=":5">{{Cite journal|last1=Schultz|first1=E. A.|last2=Haughn|first2=G. W.|date=1991-08-01|title=LEAFY, a Homeotic Gene That Regulates Inflorescence Development in Arabidopsis.|journal=The Plant Cell|language=en|volume=3|issue=8|pages=771–781|doi=10.1105/tpc.3.8.771|issn=1040-4651|pmid=12324613|pmc=160044}}</ref> Genes similar in function to LFY include ''APETALA1'' (AP1). Mutations in LFY, AP1, and similar promoting genes can cause conversion of flowers into shoots.<ref name=":1" /> 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.<ref name=":6">{{Cite journal|last1=Alvarez|first1=John|last2=Guli|first2=Catherine L.|last3=Yu|first3=Xiang-Hua|last4=Smyth|first4=David R.|date=1992-01-01|title=terminal flower: a gene affecting inflorescence development in Arabidopsis thaliana|journal=The Plant Journal|language=en|volume=2|issue=1|pages=103–116|doi=10.1111/j.1365-313X.1992.00103.x|issn=1365-313X|doi-access=free}}</ref> Both types of genes help shape flower development in accordance with the [[ABC model of flower development]]. 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.<ref name=":2">{{Cite journal|last1=Louda|first1=Svata M.|last2=Potvin|first2=Martha A.|date=1995-01-01|title=Effect of Inflorescence-Feeding Insects on the Demography and Lifetime of a Native Plant|journal=Ecology|language=en|volume=76|issue=1|pages=229–245|doi=10.2307/1940645|issn=1939-9170|jstor=1940645|bibcode=1995Ecol...76..229L }}</ref> In the absence of these herbivores, inflorescences usually produce more flower heads and seeds.<ref name=":2" /> 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.<ref name=":7">{{Cite journal|last=Moss|first=G|date=27 November 2015|title=Influence of Temperature and Photoperiod on Flower Induction and Inflorescence Development in Sweet Orange (Citrus Sinensis L. Osbeck)|journal=Journal of Horticultural Sciences|volume=44|issue=4|pages=311–320|doi=10.1080/00221589.1969.11514314}}</ref><ref>{{Cite journal|last1=Bjorkman|first1=T.|last2=Pearson|first2=K. J.|date=1998-01-01|title=High temperature arrest of inflorescence development in broccoli (Brassica oleracea var. italica L.)|journal=Journal of Experimental Botany|language=en|volume=49|issue=318|pages=101–106|doi=10.1093/jxb/49.318.101|issn=0022-0957|doi-access=free}}</ref><ref>{{Cite journal|last=BREWSTER|first=J. L.|date=1983-04-01|title=Effects of Photoperiod, Nitrogen Nutrition and Temperature on Inflorescence Initiation and Development in Onion (Allium cepa L.)|journal=Annals of Botany|language=en|volume=51|issue=4|pages=429–440|doi=10.1093/oxfordjournals.aob.a086487|issn=0305-7364}}</ref>

===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.<ref name=":0">{{Cite journal|last1=Souer|first1=E.|last2=Krol|first2=A. van der|last3=Kloos|first3=D.|last4=Spelt|first4=C.|last5=Bliek|first5=M.|last6=Mol|first6=J.|last7=Koes|first7=R.|date=1998-02-15|title=Genetic control of branching pattern and floral identity during Petunia inflorescence development|url=http://dev.biologists.org/content/125/4/733|journal=Development|language=en|volume=125|issue=4|pages=733–742|doi=10.1242/dev.125.4.733|issn=0950-1991|pmid=9435293|url-access=subscription}}</ref> Plant inflorescence architecture depends on which meristems becomes flowers and which become shoots.<ref name=":8">{{Cite journal|last1=Benlloch|first1=R.|last2=Berbel|first2=A.|last3=Serrano-Mislata|first3=A.|last4=Madueno|first4=F.|date=2007-09-01|title=Floral Initiation and Inflorescence Architecture: A Comparative View|journal=Annals of Botany|language=en|volume=100|issue=3|pages=659–676|doi=10.1093/aob/mcm146|pmid=17679690|issn=0305-7364|pmc=2759223}}</ref> 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.<ref name=":0" />

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]]'' 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.<ref>{{Cite journal|last=WYATT|first=ROBERT|date=1980-05-01|journal=New Phytologist|language=en|volume=85|issue=1|pages=119–131|doi=10.1111/j.1469-8137.1980.tb04453.x|issn=1469-8137|title=The Reproductive Biology of Asclepias Tuberosa: I. Flower Number, Arrangement, and Fruit-Set|doi-access=free|bibcode=1980NewPh..85..119W }}</ref> In ''[[Aesculus sylvatica]]'', it has been shown that the most common inflorescence sizes are correlated with the highest fruit production as well.<ref name=":4">{{Cite journal|last=Wyatt|first=Robert|date=1982-04-01|title=Inflorescence Architecture: How Flower Number, Arrangement, and Phenology Affect Pollination and Fruit-Set|journal=American Journal of Botany|language=en|volume=69|issue=4|pages=585–594|doi=10.1002/j.1537-2197.1982.tb13295.x|issn=1537-2197|jstor=2443068|bibcode=1982AmJB...69..585W }}</ref>

==References==
{{Reflist|30em}}

==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
* [[Peter F. Stevens|Stevens, P. F.]] (2001 onwards). [[Angiosperm Phylogeny Website]] [http://www.mobot.org/MOBOT/research/APweb/]. Version 7, May 2006 [and more or less continuously updated since].
* Strasburger, Noll, Schenck, Schimper: Lehrbuch der Botanik für Hochschulen. 4. Auflage, Gustav Fischer, Jena 1900, p.&nbsp;459
* [http://miosjournal.org/journal/2011/06/Inflorescences.html R J Ferry. Inflorescences and Their Names. The McAllen International Orchid Society Journal.Vol. 12(6), pp. 4-11 June 2011 ] {{Webarchive|url=https://web.archive.org/web/20180914204057/http://miosjournal.org/journal/2011/06/Inflorescences.html |date=14 September 2018 }}

==External links==
{{wiktionary | inflorescence}}
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[[Category:Flowers|Inflorescence]]
[[Category:Plant morphology]]