cyathium

thumb|right|400px|Euphorbia tridentata, cross-section of a cyathium, red stalked female flower extending toward the camera thumb|In Euphorbia milii—close up A cyathium (: 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 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 on a stalk at the base of the involucre surrounded by: Four or 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.

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