husk
Bracts or involucral sheets are special bracts in flowering plants , which usually surround several inflorescences such as basket , umbel or cyathium . The totality of the bracts of an inflorescence, which are typically approximated to (pseudo) whorls , is called the involucrum ( calyx of the capitula and cup inflorescences ; also involucrum ). More rarely, individual flowers of bracts are surrounded, for example in the kitchen clamps ( Pulsatilla ) or liverwort (Hepatica ). If they surround a single flower with a calyx , as in mallow ( malva ) and scabiosa ( scabiosa ), the involucre is called the outer calyx or envelope calyx .
Families that form bracts are particularly the daisy family (Asteraceae), the cardiac family (Dipsacaceae) and the umbelliferae (Apiaceae). In the umbelliferae, the bracts of the umbels are known as the involucellum, while those of the umbels in a double umbel are called the involucellum. In some cases the involucre is converted into a display device , as in the case of the large star umbel ( Astrantia major ), where it is conspicuously colored and serves to attract pollinators. In the case of the burdock ( Arctium ), the bracts are transformed into Velcro devices so that they adhere to the fur of animals and thus serve to spread .
literature
- Manfred A. Fischer , Karl Oswald, Wolfgang Adler: Excursion flora for Austria, Liechtenstein and South Tyrol. 3rd, improved edition. State of Upper Austria, Biology Center of the Upper Austrian State Museums, Linz 2008, ISBN 978-3-85474-187-9 , p. 76.
Individual evidence
- ^ Gerhard Wagenitz : Dictionary of Botany. The terms in their historical context. 2nd, expanded edition. Spektrum Akademischer Verlag, Heidelberg / Berlin 2003, ISBN 3-8274-1398-2 , p. 161.
- ↑ Peter Leins: Blossom and Fruit. Morphology, history of development, phylogeny, function, ecology. E. Schweizerbart'sche Verlagsbuchhandlung, Stuttgart 2000, ISBN 3-510-65194-4 , p. 302.
