Our Clark County specimen is from a fallow field and that from Martin County is from a wheat stubble field. Pepoon reports it as found in Lake County along the Wabash Railroad at Miller. Kriebel has collected it in Lawrence County and in 1929 Bechtel collected it in Montgomery County. This species also seems to be adventive from the south.
Annual, to 1 m, sparingly and somewhat umbellately branched above; lvs narrowly triangular to oblong, lanceolate, or ovate-oblong, 4-10 cm, the principal ones with the blade rounded at base and less than twice as long as the petiole; fls in dense terminal infls 1-3 cm; staminate fls with 5 sep, 5 pet, and 10-14 stamens; pistillate fls apetalous, the 6-10 sep accrescent to 1 cm; styles 3, each 2-3 times dichotomous, the stigmas thus 12-24; 2n=20. Dry, usually sandy soil and waste places; O. to Ind. and Neb., s. to Fla. and Tex. Ours are var. capitatus.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.