Editing Asteraceae (section)

===Inflorescences<span class="anchor" id="Flowers"></span>===
{{More citations needed section|date=February 2021}}

Nearly all Asteraceae bear their flowers in dense flower heads called ''capitula''. They are surrounded by [[bract#Involucral bracts|involucral bracts]], and when viewed from a distance, each capitulum may appear to be a single flower. Enlarged outer (peripheral) flowers in the capitulum may resemble petals, and the involucral bracts may look like a calyx.<ref>{{Cite journal |last1=Elomaa |first1=Paula |last2=Zhao |first2=Yafei |last3=Zhang |first3=Teng |date=2018-07-01 |title=Flower heads in Asteraceae—recruitment of conserved developmental regulators to control the flower-like inflorescence architecture |journal=Horticulture Research |language=en |volume=5 |issue=1 |page=36 |doi=10.1038/s41438-018-0056-8 |pmid=29977572 |issn=2052-7276|pmc=6026493 |bibcode=2018HorR....5...36E }}</ref> Notable exceptions include ''[[Hecastocleis|Hecastocleis shockleyi]]'' (the only species in the subfamily Hecastocleidoideae)<ref name=EoL>{{cite web|website= Encyclopedia of Life|title= Hecastocleis shockleyi A. Gray|url= http://eol.org/pages/467045/details|access-date= 2016-01-02}} and {{cite book|first1= Vicki A.|last1= Funk|first2= D.J. Nicholas|last2= Hind|chapter= Chapter 16. Hecastocleideae (Hecastocleidoideae)|title= Systematics, Evolution, and Biogeography of Compositae|publisher= [[International Association for Plant Taxonomy]]|location= Vienna|editor1= V.A. Funk|editor2=A. Susanna |editor3=T. Stuessy |editor4=R. Bayer|url= http://botany.si.edu/BDG/pdf/funkyarchive/funkypdf/2009_pr_Funk_Hind_Hecastocleideae.pdf|access-date= 2016-01-02}}</ref> and the species of the genus ''[[Corymbium]]'' (the only genus in the subfamily Corymbioideae),<ref name= Weitz>{{cite journal|first= F.M.|last= Weitz|year= 1989|title= A revision of the genus Corymbium (Asteraceae)|journal=[[South African Journal of Botany]]|volume= 55|issue= 6|pages= 598–629|doi= 10.1016/S0254-6299(16)31133-4|bibcode= 1989SAJB...55..598W|url= https://core.ac.uk/download/pdf/82290441.pdf}}</ref> which have one-flowered bisexual capitulas, ''[[Gundelia]]'' with one-flowered unisexual capitulas,<ref>{{cite book|last= Feinbrun-Dothan|first= N.|year= 1978|title= Flora Palaestina|volume= 3|location= Jerusalem}} cited on {{cite web|website= cichorieae portal|title= Gundelia|url= http://cichorieae.e-taxonomy.net/portal/cdm_dataportal/taxon/fb808979-f281-4e66-90d7-54496a59871f|accessdate= 2016-12-15}}</ref> and [[Gymnarrhena|Gymnarrhena micrantha]] with one-flowered female capitulas and few flowered male capitulas.<ref name=FFS>{{cite book|first1= Vicki A.|last1= Funk|first2= Ori|last2= Fragman-Sapir|year= 2009|chapter= 22. Gymnarrheneae (Gymnarrhenoideae)|title= Systematics, Evolution, and Biogeography of Compositae|publisher= [[International Association for Plant Taxonomy]]|location= Vienna|editor1= V.A. Funk |editor2=A. Susanna |editor3=T. Stuessy |editor4=R. Bayer|pages= 327–332|chapter-url= https://botany.si.edu/bdg/pdf/funkyarchive/funkypdf/2009_pr_Funk_Fragman-Sapir_Gymnarrheneae.pdf|access-date= 2016-12-27}}</ref>

==== Floral heads ====
[[File:Bidens flwr.jpg|thumb|right|300px|A typical Asteraceae flower head showing the (five) individual ray florets and the (approximately 16) disk florets of a specimen of (''[[Bidens torta]]'')]]

In plants of the Asteraceae, what appears to be a single "daisy"-type flower is actually a composite of several much smaller flowers, known as the ''capitulum'' or ''head''. By visually presenting as a single flower, the capitulum functions in attracting pollinators, in the same manner that other "showy" flowering plants in numerous other, older, plant families have evolved to attract pollinators. The previous name for the family, ''Compositae'', reflects the fact that what appears to be a single floral entity is in fact a ''composite'' of much smaller flowers.<ref name=CDF/>

The "petals" or "sunrays" in an "asteraceous" head are in fact individual strap-shaped<ref name=MDW/> flowers called ''ray flowers'' or ''ray florets'', and the "sun disk" is made up of smaller, [[radial symmetry|radially symmetric]], individual flowers called ''disc flowers'' or ''disc florets''. The word ''aster'' means "star" in Greek, referring to the appearance of most family members as a "celestial body with rays".
The capitulum, which often appears to be a single flower, is often referred to as a ''head''.<ref name=Spellenberg2001 /> In some species, the entire head is able to pivot its floral stem in the course of the day to track the sun (like a "smart" solar panel), thus maximizing the reflectivity of the entire floral unit and further attracting flying pollinators.<ref name=CDF/>

Nearest to the flower stem lie a series of small, usually green, scale-like [[bract]]s. These are known as ''[[phyllary|phyllaries]]''; collectively, they form the [[involucre]], which serves to protect the immature head of florets during its development.{{r|CDF|p=29}} The individual florets are arranged atop a dome-like structure called the ''receptacle''.{{r|CDF}}

The individual florets in a head consist, developmentally, of five fused petals (rarely four); instead of [[sepal]]s, they have threadlike, hairy, or bristly structures,<ref name=Spellenberg2001 /> known collectively as a ''[[Pappus (flower structure)|pappus]]'', (plural ''pappi''). The pappus surrounds the ovary and can, when mature and attached to a seed, adhere to animal fur or be carried by air currents, aiding in seed dispersal. The whitish, fluffy head of a [[dandelion]], commonly blown on by children, consists of numerous seeds resting on the receptacle, each seed attached to its pappus. The pappi provide a parachute-like structure to help the seed travel from its point of origin to a more hospitable site.<ref name=CDF/>

[[File:Leucanthemum diagram.svg|thumb|upright=3|center|alt=refer to caption|Schemes and floral diagrams of the different floret types of the Asteraceae: ''[[Leucanthemum vulgare]]'': a = disc flower; b = ray flower.<br>
1 – [[Style (botany)|style]] with [[Stigma (botany)|stigmas]]<br>
2 – [[anther]]s
<br>3 – corolla ([[petal]]s); typically, in the ray flower, three petals are joined to form a strap (in other species, five petals can fuse to form a ''ligule'')<br>
4 – reduced [[Calyx (botany)|calyx]]<br>
4’ – ''Carduus acanthoides'' (left shaded circle): [[pappus (flower structure)|pappus]]: in many Asteraceae species, the calyx develops as a fibrous or bristly pappus<br>
5 – [[inferior ovary]]: fused ovary consisting of two [[carpel]]s, containing one [[Abaxial (botany)|abaxial]] [[ovule]] ([[basal placentation]]).]]

A ''ray flower'' is a two- or three-lobed, strap-shaped, individual flower, found in the head of most members of the Asteraceae.<ref name=CDF/><ref name=MDW/> The [[Petal|corolla]] of the ray flower may have two tiny, [[vestigial]] teeth, opposite to the three-lobed strap, or tongue, indicating its evolution by fusion from an ancestral, five-part corolla. In some species, the 3:2 arrangement is reversed, with two lobes, and zero or three tiny teeth visible opposite the tongue.

A ''ligulate flower'' is a five-lobed, strap-shaped, individual flower found in the heads of certain other asteraceous species.<ref name=CDF/> A ''ligule'' is the strap-shaped tongue of the corolla of either a ray flower or of a ligulate flower.{{clarify|date=April 2023}}{{example needed|date=April 2023}}<ref name=MDW/> A ''disk flower'' (or ''disc flower'') is a radially symmetric individual flower in the head, which is ringed by the ray flowers when both are present.<ref name=CDF/><ref name=MDW/> In some species, ray flowers may be arranged around the disc in irregular symmetry, or with a weakly [[bilateral symmetry|bilaterally symmetric]] arrangement.<ref name=CDF/>