Parthenium integrifolium L.

Perennial 3–10 dm from a tuberous-thickened, usually short root; stem simple or branched above, strigose-puberulent above, often glabrous below; lvs large and sometimes few, crenate-serrate, or sublyrate at base, scabrous to subglabrous, the basal long-petiolate, with lance-elliptic to broadly ovate blade 7–20 × 4–10 cm, the cauline progressively shorter-petiolate and generally reduced, the upper often sessile and clasping, but less conspicuously so than in the next 2 spp.; heads numerous in a flat-topped infl, the disk 4–7 mm wide; rays scarcely 2 mm; achenes obovate, black, 3 mm; 2n=72. Prairies and dry woods; Va. to se. Minn., s. to Ga. and Ark., and adventive in Mass. June–Sept.

Prairies, rock outcrops and roadsides in arid and semi-arid environments. Glades and barrens, prairies, disturbed sites at elevations of 10-500 metres.

Can be grown by cuttings or seedlings.