A cyathium (plural: cyathia) is one of the specialised pseudanthia ("false flowers") forming the inflorescence of plants in the genus Euphorbia (Euphorbiaceae). A cyathium consists of:
Five (rarely four) bracteoles. These are small, united bracts, which form a cup-like involucre. Their upper tips are free and in the beginning cover the opening of the involucre (like the shutter of a camera). These alternate with:
Five (1 to 10) nectar glands, which are sometimes fused.
One extremely reduced female flower standing in the centre at the base of the involucre, consisting of an ovary on a short stem with pistil, and surrounded by:
Five groups (one group at the base of each bracteole) of extremely reduced male flowers, which each consist of a single anther on a stem.
Euphorbia tridentata, cross-section of a cyathium.In euphorbia milii-large
The flower-like characteristics of the cyathia are underlined by brightly coloured nectar glands and often by petal-like appendages to the nectar glands, or brightly coloured, petal-like bracts positioned under the cyathia. The paired petal-like bracts of Euphorbia section Goniostema are called cyathophylls. here female to male flower ratio is 1:α
The cyathia are sometimes solitary, but are usually in cymes, inflorescences of the second order, in pseudumbels, on dichotomously branched stalks or in so-called simple cymes which consist of one central and two lateral cyathia.
In one group of Madagascan species in the subfamily Euphorbia section Goniostema (E. aueoviridiflora, E. capmanambatoensis, E. iharanae, E. leuconeura, E. neohumbertii, E. viguieri) there is a tendency for a further pseudanthium to grow from the cyme. Probably as an adaptation to pollination by birds, the cyathia have become specialised: Most cyathia have upright cyathophylls which surround them protectively, but render the nectar glands inaccessible. To compensate, between them are naked sterile cyathia whose only job is to produce nectar.
Referencesedit
(in Italian) Sandro Pignatti, Flora d'Italia, Edagricole, Bologna 1982. ISBN88-506-2449-2
December 18, 2023
cyathium, confused, with, cyathea, cyathus, this, section, needs, additional, citations, verification, please, help, improve, this, article, adding, citations, reliable, sources, this, section, unsourced, material, challenged, removed, april, 2022, learn, when. Not to be confused with Cyathea or Cyathus This section needs additional citations for verification Please help improve this article by adding citations to reliable sources in this section Unsourced material may be challenged and removed April 2022 Learn how and when to remove this template message A cyathium plural cyathia is one of the specialised pseudanthia false flowers forming the inflorescence of plants in the genus Euphorbia Euphorbiaceae A cyathium consists of Five rarely four bracteoles These are small united bracts which form a cup like involucre Their upper tips are free and in the beginning cover the opening of the involucre like the shutter of a camera These alternate with Five 1 to 10 nectar glands which are sometimes fused One extremely reduced female flower standing in the centre at the base of the involucre consisting of an ovary on a short stem with pistil and surrounded by Five groups one group at the base of each bracteole of extremely reduced male flowers which each consist of a single anther on a stem Euphorbia tridentata cross section of a cyathium In euphorbia milii large The flower like characteristics of the cyathia are underlined by brightly coloured nectar glands and often by petal like appendages to the nectar glands or brightly coloured petal like bracts positioned under the cyathia The paired petal like bracts of Euphorbia section Goniostema are called cyathophylls here female to male flower ratio is 1 aThe cyathia are sometimes solitary but are usually in cymes inflorescences of the second order in pseudumbels on dichotomously branched stalks or in so called simple cymes which consist of one central and two lateral cyathia In one group of Madagascan species in the subfamily Euphorbia section Goniostema E aueoviridiflora E capmanambatoensis E iharanae E leuconeura E neohumbertii E viguieri there is a tendency for a further pseudanthium to grow from the cyme Probably as an adaptation to pollination by birds the cyathia have become specialised Most cyathia have upright cyathophylls which surround them protectively but render the nectar glands inaccessible To compensate between them are naked sterile cyathia whose only job is to produce nectar References edit in Italian Sandro Pignatti Flora d Italia Edagricole Bologna 1982 ISBN 88 506 2449 2 Retrieved from https en wikipedia org w index php title Cyathium amp oldid 1160462081, wikipedia, wiki, book, books, library,
