Usually the leaves are reduced, with only the lower leaf well developed (vaginal bracts). But there are also bracts which, in the reduction of the entire organ, mainly consist of the spider part (laminar bracts).
In addition, they often serve to attract insects, in these cases bracts only differ in color from the leaves (a well-known example of this is the poinsettia ). In a broader sense, the petals of the perianth are also just a special case of bracts. Bracts can assimilate as long as they are green. However, the original leaf function often takes a back seat to the envelope function. Such bracts initially enclose the flower bud, but can still stand away from the unfolded flower after the uppermost stem section has been stretched.
The bracts and bracts of flowers or partial inflorescences are often designed as bracts, that "brakteos". However, bracts are not necessarily bracts of side shoots or flowers and, conversely, bracts are not always bract-like.
In some species with inconspicuous flowers, it is conspicuously colored bracts, which instead of the flower envelope take on the function of attracting pollinators . Then the bracts are poor in chlorophyll or free of chlorophyll (loss of assimilation function). Forming a plurality of bracts a goblet-like shell around an inflorescence, so one also speaks of bracts .
Bract of poinsettia (Euphorbia pulcherrima) with striking red coloration
Three purple bracts of the triplet flower ( Bougainvillea )
Spathiphyllum forms a white bract next to the actual flower
- Klaus Napp-Zinn: Handbook of Plant Anatomy. Borntraeger, Stuttgart 1988, ISBN 3-443-14015-7 .
- James D. Mauseth: Botany. An Introduction to Plant Biology. 4th edition. Jones & Bartlett, Sudbury MA 2008, ISBN 978-0-7637-5345-0 .