Bract
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In botany, a bract is a modified or specialized leaf, especially one associated with a reproductive structure such as a flower, inflorescence axis, or cone scale. Bracts are often (but not always) different from foliage leaves, for example being smaller, larger, or of a different color or texture.
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), which has small green flowers, surrounded by large scarlet bracts.
A small bract is called a bracteole or bractlet. Technically this is any bract that arises on a pedicel instead of subtending it.
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 removed from cereal grain during threshing and winnowing.
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 Apiaceae, Asteraceae, Dipsacaceae and Polygonaceae. Each flower in an inflorescence may have its own whorl of bracts, in this case called an involucel. In addition to these, many asteraceous plants also have bracts at the base of each flower. In this case the bracts at the base of the inflorescence or head (involucral bracts or phyllaries) are scales or leaf-like structures, while those at the flower base (chaff, paleas or receptacular bracts) are usually minute scales or bristles.
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 palms and arums. 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 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, they extend beyond the cone scales, even in mature cones.
[edit] Gallery
 Beggar-tick (Bidens comosa): narrow involucral bracts surround each inflorescence, each of which also has a single bract below it, then there is a pair of leafy bracts on the main stem and below those a pair of leaves. |
 Bracts surrounding a banana flower stalk |
 In Bougainvillea each cluster of three flowers is surrounded by three or six colorful bracts |
 Bright red bracts surrounding the inflorescence of poinsettia (Euphorbia pulcherrima) |
 Yellow petal-like bracts of Euphorbia epithymoides |
 Euphorbia milii var. vulcanii cyathia bearing a pair of pinkish cyathophylls |
 Green involucral bracts surrounding the bud of a sunflower (Helianthemum annuum) |
 Showy white bracts of the Kousa Dogwood Cornus kousa |
 Large pink bracts of an Anthurium |
 Colourful bracts of Ananas bracteatus |
