involucre

noun

(L. involucrum: cover, wrap) A protective structure in some flowering plants and bryophytes. In flowering plants it consists of a ring of bracts arising beneath the flower cluster of those species with a capitulum (i.e. members of the dandelion family) or an umbel (i.e. members of the carrot family). In mosses and liverworts the involucre is a projection of tissue from the thallus that arches over the developing archegonium. In Hymenophyllaceae, a layer of tissue enveloping the sporangia. Syn. involucrum.