HAWKWEED, the name given to species of the genus Hieracium, of the family Compositae, containing some 45o species inhabiting the northern hemisphere, South Africa and the Andes. The flowering heads, generally yellow, are borne, often several at a time, on an elongated axis, the component flowers being ligulate. Various hawkweeds are troublesome weeds, especially in grass land. Some 20 or more species occur in the British Isles and upwards of 4o species are found in North America, including several from the Old World which are widely naturalized as weeds. Of the latter, the orange hawkweed or devil's paint-brush (H. aurantiacum), of south Europe, sometimes cultivated, and the field hawkweed (H. pratense) have become pestiferous. G. Men del (q.v.) employed hawkweeds in some of his experiments in heredity, but they proved extremely unsatisfactory material on account of the small size of the individual flowers and because some are parthenogenetic. (See COMPOSITAE.)