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a type of inflorescence characteristic of plants of the family Euphorbiaceae. A cyathium consists of a terminal apetalous pistillate flower surrounded by five groups (compound monochasium) of staminate flowers. Each flower has a single stamen whose anther filament is joined to the flower stalk. The inflorescence is enclosed by a cuplike involucre with nectar glands. A cyathium resembles a single flower (anthodium).