Bract
612098
193841099
2008-02-25T02:43:04Z
Curtis Clark
302909
Add information and clarify
{{Unreferenced|date=May 2007}}
[[Image:Yellow-rattle close 700.jpg|thumb|300px|right|Toothed bracts on ''Rhinanthus minor'']]
In [[botany]], a '''bract''' is a modified or specialized [[leaf]]. Bracts are ordinarily associated with reproductive structures (subtending [[flower]]s, [[inflorescence]] axes, or [[cone scale]]s). They are ordinarily reduced in size relative to foliage leaves, or of a different color or texture from foliage leaves, or both.
Some bracts are brightly colored and serve the function of attracting pollinators, either in concert with or instead of the [[perianth]]. An excellent example of this latter type of bract occurs in the [[Poinsettia]] plant (''Euphorbia pulcherrima'').
A small bract is called '''bracteole''' or bractlet. Technically it is any bract that arises on a pedicel instead of subtending it. In grasses, the bracts that enclose the florets are termed '''[[Chaff|glume]]s'''.
Bracts that appear in a whorl subtending an inflorescence are collectively called an '''involucre'''. An involucre is a common feature under the inflorescences of many [[Apiaceae]], [[Asteraceae]], and [[Polygonaceae]]. Each flower in an inflorescence may have its own whorl of bracts, in this case called an '''involucel'''. Many [[Asteraceae|asteraceous]] plants have bracts both at the flower base and inflorescence base. Those at the flower base — '''[[chaff]]''' (paleae or receptacular bracts) — are usually minute scales or bristles. Those at the base of the inflorescence or [[head (botany)|head]] — the '''involucral bracts''' (phyllaries) — are often green, narrow, and leafy.
A '''prophyll''' is a leaf-like structure, such as a bracteole, subtending a single flower or pedicel. The term can also mean the lower bract on a peduncle.
A '''[[spathe]]''' is a large bract that forms a sheath to enclose the flower cluster of certain plants such as [[Arecaceae|palm]]s and [[arum]]s. In many arums, the spathe is petal-like, attracting pollinators to the flowers arranged on a type of spike called a [[spadix]].
The frequently showy pair of bracts of [[cyathium|cyathia]] of ''[[Euphorbia]]'' species in subgenus ''Lacanthis'' is termed '''cyathophylls'''.
Bracts subtend the cone scales in the seed cones of many [[conifer]]s, and in some cases, such as [[Pseudotsuga]], extend beyond the cone scales even in mature cones.
== Gallery ==
<gallery>
Image:Leafy-bract-Beggar-ticks.we.jpg|Bracts on Leafy-bract Beggar-tick (''Bidens comosa'')
Image:Banana bract.jpg|Bracts surrounding a [[banana]] flower stalk
Image:Bougainvilla.jpg|In [[Bougainvillea]] each cluster of three flowers is surrounded by three or six more colorful bracts
Image:E pulcherrima ies.jpg|Bright red bracts of ''[[Euphorbia pulcherrima]]'' (Poinsettia)
Image:E epithymoides ies.jpg|Yellow petal-like bracts of ''[[Euphorbia epithymoides]]''
Image:E milii vulcanii ies.jpg|''[[Euphorbia milii var. vulcanii]]'' cyathia bearing a pair of pinkish cyathophylls
Image:Sunflower opening 2-KayEss-2.jpeg|Green bracts surrounding a [[sunflower]] bud
Image:Cornus kousa flowers img 2068.jpg|Showy white bracts of the [[Kousa Dogwood]] ''Cornus kousa''
Image:Pink anthurium.jpg|Large pink bracts of an ''[[Anthurium]]''
Image:Ananas bracteatus var tricolor.jpg|Colourful bracts of ''[[Ananas bracteatus]]''
</gallery>
[[Category:plant morphology]]
[[de:Hochblatt]]
[[de:Tragblatt]]
[[es:Bráctea]]
[[eo:Brakteo]]
[[fr:Bractée]]
[[id:Daun pelindung]]
[[it:Brattea]]
[[nl:Schutblad (plant)]]
[[pl:podsadka]]
[[pt:Bráctea]]
[[tr:Brahte]]