A Cyathium is one of the specialised pseudanthia forming the inflorescence of plants in the genus Euphorbia (Euphorbiaceae). A cyathium consists of:Five bracteoles. These are small, united bracts, which form a cup-like involucre. Their upper tips are free and cover the opening of the involucre. These alternate with: Five 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 of extremely reduced male flowers, which each consist of a single anther on a stem.