cyath-, cyatho-, cyathi- +

(Greek: cup, a goblet, a cup for measuring, or drawing wine out of a bowl)

cyathiform
Cup-shaped; in the form of a cup, a little widened at the top.
cyathium
An inflorescence (group of flowers produced by a plant) consisting of a cup-like cluster of modified leaves enclosing a female flower and several male flowers, as in the poinsettia.
cyathophorous
1. Cup-shaped.
2. An inflorescence (the flowering part of a plant, and especially the mode of its arrangement) with unisexual (either pistillate [female] or staminate [male]) flowers surrounded by a cup-like cluster of involucral bracts, e.g., a poinsettia.

Involucre refers to a circle or collection of bracts surrounding a flower cluster or head, or a single flower.

cyathus
A small cup-shaped organ.