The protective cap or hood covering the spore case of a moss or related plant.
A similar hoodlike or caplike structure, such as a root cap.
The remains of the female sex organ, or archegonium, of a moss, forming the protective caplike covering of the spore case.
Any similar protective hood, cap, or covering of a fruit, flower, or root.
In some bryophyte plants, a structure that covers the young sporophyte as it develops within the tissues of its gametophyte parent. The calyptra, which consists of a thickening of the archegonium walls, eventually breaks open as the spore capsule grows.
Origin of calyptra
Medieval Latin from Greek kaluptra veil from kaluptein to cover kel-1 in Indo-European roots