Bract

{{Short description|Modified or specialized leaf}} {{Redirect|Involucre|the protective layer that encloses spores in fungi|Peridium|the indusium in ferns or fungi|Sorus}}

[[Image:Yellow-rattle close 700.jpg|thumb|Papery (upper) and leafy bracts on ''Rhinanthus minor'' (hay rattle). All the "leaves" in this image are bracts.]]

In botany, a '''bract''' is a modified or specialized leaf, associated with a reproductive structure such as a flower, inflorescence axis or cone scale. Bracts are usually different from foliage leaves in size, color, shape or texture. They also look different from the parts of the flower, such as the petals or sepals.

A plant having bracts is referred to as '''bracteate'''<ref>{{Cite web|url=http://www.dictionary.com/browse/bracteate|title=the definition of bracteate|website=Dictionary.com|access-date=2017-04-27|url-status=live|archive-url=https://web.archive.org/web/20170428051604/http://www.dictionary.com/browse/bracteate|archive-date=2017-04-28}}</ref> or '''bracteolate''', while one that lacks them is referred to as '''ebracteate'''<ref>{{Cite web|url=http://www.greengonzo.com/dictionary/Ebractiate.html|title=Definition of Ebractate|website=www.greengonzo.com|access-date=2017-04-27|url-status=live|archive-url=https://web.archive.org/web/20170428052240/http://www.greengonzo.com/dictionary/Ebractiate.html|archive-date=2017-04-28}}</ref> or '''ebracteolate'''.

==Variants==

Some bracts are brightly coloured which aid in the attraction of pollinators, either together with the perianth or instead of it. Examples of this type of bract include those of ''Euphorbia pulcherrima'' (poinsettia) and ''Bougainvillea'': both of these have large colourful bracts surrounding much smaller, less colourful flowers.<ref>{{cite book |title=Environment Southwest |date=1986 |publisher=San Diego Society of Natural History |url=https://books.google.com/books?id=tpsbAQAAIAAJ |language=en}}</ref>

In grasses, each floret (flower) is enclosed in a pair of papery bracts, called the '''lemma''' (lower bract) and '''palea''' (upper bract), while each spikelet (group of florets) has a further pair of bracts at its base called '''glumes'''. These bracts form the chaff that is usually removed from cereal grain during threshing and winnowing.<ref>{{cite book |last1=Jensen |first1=William August |last2=Salisbury |first2=Frank B. |title=Botany: an Ecological Approach |date=1972 |publisher=Wadsworth Publishing Company |isbn=978-0-534-00092-9 |page=544 |language=en}}</ref>

Bats may detect acoustic signals from dish-shaped bracts such as those of ''Marcgravia evenia''.<ref name=Simon11>{{cite journal|author=Ralph Simon|author2=Marc W. Holderied|author3=Corinna U. Koch|author4=Otto von Helversen|s2cid=5035286|title=Floral acoustics: Conspicuous echoes of a dish-shaped leaf attract bat pollinators|journal=Science|volume= 333| issue=6042|pages=631–633|doi=10.1126/science.1204210|pmid=21798950|year=2011|bibcode=2011Sci...333..631S}}</ref>

A '''prophyll''' is a leaf-like structure, such as a bracteole, subtending (extending under) a single flower or pedicel. The term can also mean the lower bract on a peduncle.

The frequently showy pair of bracts of ''Euphorbia'' species in subgenus ''Lacanthis'' are the '''cyathophylls'''.

Bracts subtend the cone scales in the seed cones of many conifers, and in some cases, such as ''Pseudotsuga'', extend beyond the cone scales.

{{gallery|mode=packed |Castilleja levisecta bracts.jpg|The yellow bracts of ''Castilleja levisecta'' press tight against the stem. |Bougainvillea glabra.JPG|The bracts of ''Bougainvillea glabra'', differ in colour from leaves and attract pollinators. |Banana bract.jpg|Bracts along a banana flower stalk surround rows of flowers |E milii vulcanii ies.jpg|''Euphorbia milii'' var. ''vulcanii'' cyathia bearing a pair of pinkish cyathophylls |Ananas bracteatus var tricolor.jpg|Colourful bracts of ''Ananas bracteatus'' |Erigeron peregrinus 6287.JPG|The many green involucral bracts of ''Erigeron peregrinus'' taper to a point and are linear, loose, and about the same length. |Blooming Dogwood.jpg|Dogwood species ''Cornus florida'' inflorescence showing four large white bracts and central flower cluster |2013-05-10 08 26 08 Closeup of pink dogwoods at the Brendan T. Byrne State Forest headquarters.jpg|''Cornus florida'' dogwood cultivar with pink bracts surrounding yellow florets |豔紅苞鳳梨 20190712192436.jpg|The red bracts of ''Aechmea bracteata'' |女王鬱金 20190715203108 01.jpg|The pink bracts of ''Curcuma petiolata'' |火鶴 20190729181532.jpg|The pink bract of ''Anthurium andraeanum'' 'Pink Lady' |豔山姜花序總苞 20190508131956.jpg|''Alpinia zerumbet'' flower buds protected by two bracts |地湧金蓮 Musella lasiocarpa 20201028130818 01.jpg|The golden bracts of ''Musella lasiocarpa'' }}

== Bracteole== A small bract is called a '''bracteole''' or '''bractlet'''. Technically this is any bract that arises ''on'' a pedicel instead of subtending it.

== Involucral bracts == [[Image:Leafy-bract-Beggar-ticks.we.jpg|upright|thumb|Beggar-tick (''Bidens comosa'')]]

Bracts that appear in a whorl subtending an inflorescence are collectively called an '''involucre'''. An involucre is a common feature beneath the inflorescences of many families, including the Apiaceae (carrot family), Asteraceae (sunflower or the daisy family), Dipsacaceae, and Polygonaceae. Each flower in an inflorescence may have its own whorl of bracts, in this case called an '''involucel'''. They can be called ''chaff'', ''paleas'' or ''receptacular bracts'' and are usually minute scales or bristles. Many asteraceous plants have bracts at the base of each inflorescence.<ref name=":0">{{Cite report |title=Bidens frondosa (beggarticks) |last=Popay |first=I |date=2022-01-07 |doi=10.1079/cabicompendium.108916 |language=en|doi-access=free }}</ref>

The term '''involucre''' is also used for a highly conspicuous bract or bract pair at the base of an inflorescence. In the family Betulaceae, notably in the genera ''Carpinus'' and ''Corylus'', the '''involucre''' is a leafy structure that protects the developing nuts. Beggar-tick (''Bidens comosa'') has narrow involucral bracts surrounding each inflorescence, each of which also has a single bract below it. There is then a pair of leafy bracts on the main stem and below those a pair of leaves.<ref name=":0" /> {{clear}}

[[Image:Hibiscus rosa-sinensis3 ies.jpg|thumb|upright|Epicalyx of ''Hibiscus rosa-sinensis'']] ==Epicalyx== An epicalyx (which forms an additional whorl around the calyx of a single flower) is a modification of bracteoles.<ref>{{cite book|last=Darpan|first=Pratiyogita|title=Competition Science Vision|date=June 2006|publisher=Pratiyogita Darpan|page=136}}</ref> In other words, the epicalyx is a group of bracts resembling a calyx or bracteoles forming a whorl outer to the calyx.<ref>{{cite web |url=http://www.textbooksonline.tn.nic.in/books/12/std12-botany-em.pdf |title=Botany |access-date=2010-08-15 |url-status=dead |archive-url=https://web.archive.org/web/20101214091359/http://www.textbooksonline.tn.nic.in/Books/12/Std12-Botany-EM.pdf |archive-date=2010-12-14 }}</ref>{{page needed|date=July 2025}} It is a calyx-like extra whorl of floral appendages. Each individual segment of the epicalyx is called an '''episepal''' because they resemble the sepals in them.<ref>{{cite web |url=http://botanydictionary.org/epicalyx.html |title=epicalyx – Dictionary of botany |publisher=Botanydictionary.org |access-date=2012-04-29 |url-status=live |archive-url=http://archive.wikiwix.com/cache/20120501223013/http://botanydictionary.org/epicalyx.html |archive-date=2012-05-01 }}</ref> They are present in the hibiscus family, Malvaceae. ''Fragaria'' (strawberries) may or may not have an epicalyx.

[[Image:Anthurium scherzerianum 2.jpg|thumb|upright|''Anthurium scherzerianum'' inflorescence with spathe and spadix]] ==Spathe==

A ''spathe'' is a large bract or a pair of bracts that forms a sheath to enclose the flower cluster of plants such as palms, arums, irises,<ref name=Lynch>Richard Lynch {{Google books|grvYTul5CSUC|The Book of the Iris|page=203}}</ref> crocuses<ref>Alex Casha {{Google books|Poo9CgAAQBAJ|Flora of the Maltese Islands|page=287}}</ref> and dayflowers (''Commelina''). ''Zephyranthes tubispatha'' in the Amaryllidaceae derives its specific name from its tubular spathe. In many arums (family Araceae), the spathe is petal-like, attracting pollinators to the flowers arranged on a type of spike called a spadix.

== See also == * Glossary of botanical terms * Nectary

== References == {{Reflist}}

==External links== *{{Commons category inline}}

Category:Plant morphology Category:Leaves