(redirected from involucral)
Also found in: Dictionary, Thesaurus, Medical, Wikipedia.
Related to involucral: bracteole


Bracts forming one or more whorls at the base of an inflorescence or fruit in certain plants.



the small, tightly packed apical leaves that surround an inflorescence. In plants of the families Compositae and Dipsacaceae, the involucre closely surrounds the inflorescence; as a result, the involucre and the inflorescence appear to form a single flower. In plants of the family Umbelliferae, the involucre is located at the base of the inflorescences, or compound umbels. The leaves at the base of a simple umbel form an involucel. The morphological characteristics of involucres and involucels are used in the taxonomy of the various families.

References in periodicals archive ?
Several species of Corylus have the involucral bracts finely divided to produce a spiny bur that encloses the nut (Crane, 1989).
Capitulum: A condensed type of indeterminate inflorescence in which all of the flowers are sessile and are located on a receptacle and are subtended involucral bracts (phyllaries).
Despite the reduction in flower number, primary capitula in such a syncephalium retain their individual involucral bracts, an indication of their true nature.
This "transition apex" is distinguished from the vegetative apex by its larger size and broader shape but lacks apical derivatives such as involucral bract primordia, floral primordia, or receptacular bract primordia (Popham, 1964; Popham & Chan, 1952).
For instance, initiation of involucral bract primordia was found to herald the irreversibility of the Chrysanthemum morifolium inflorescence meristem (Horridge & Cockshull, 1979).
In Echinops, the first sign of this basipetal differentiation is the production of involucral bracts subtending each single-flowered primary capitulum (Leins & Gemmeke, 1979).