INVOLUCRE. The whorl of bracts at the base of the in florescences or general umbel in umbelliferous plants is called a general involucre; the similar leafy whorl adjoining the smaller umbels or umbellules being termed an involcel or partial in volucre. In Compositae the name is applied to the bracts sur rounding the head of the flower characteristic of this family and Umbelliferae. See FLOWER, UMBELLIFERAE and COMPOSITAE.