Ambrosia psilostachya var. coronopifolia (Torr. & A. Gray) Farw. ex Fern.

Ambrosia coronopifolia T. & G. Fl. N. Am. 2: 291. 1842
Ambrosia hispida Torr. Ann. Lye. N. Y. 2: 216. 1827. Not A. hispida Pursh, 1814. Ambrosia psilostachya A. Grav, Syn. Fl. N. Am. I s : 250, mainly. 1884. Not A. psilostachya DC. 1836.
A perennial herb, with a creeping rootstock; stem 3-10 dm. high, branched above, striate, hirsute with appressed or ascending hairs; leaves ovate in outline, pinnatifid, subsessile or the lower with short winged petioles, strigose and glandular-granuliferous on both sides, the divisions lanceolate or oblong-lanceolate, acute, or those of the lower leaves obtuse, often lobed; staminate heads very numerous, in racemes terminating the branches; involucre oblique, broadly obconic, 3-3.5 mm. broad, slightly shorter than the flowers, hispid-strigose, crenate on the margins; paleae of the receptacle filiform; corolla puberulent; pistillate heads solitary or 2 or 3 together in the axils of the upper leaves; body of the fruit 3 mm. long, obovoid, indistinctly rugose, hirsute; beak conic, scarcely more than 0.5 mm. long; spines wanting or 1-4, very short and blunt.
Type locality: Prairies of Illinois.
Distribution: Illinois and Michigan to Saskatchewan, Idaho, and northern Mexico; introduced in Connecticut.