Conyza coulteri A. Gray, Proc. Amer. Acad. Arts 7: 355. 1868

Annuals, 10–150 cm. Leaf blades: bases ± clasping, faces usually both hirtellous to villous and ± gland-ular-viscid; proximal broadly spatulate to oblong, 20–50 × 10–20 mm, obscurely lobed or coarsely toothed; distal oblong to elliptic, 10–20 × 3–10 mm, coarsely toothed from near bases or entire. Heads in racemiform-paniculiform arrays. Involucres 2.5–3+ mm. Receptacles 2–3 mm diam. Pistillate florets 60–100+; corollas: lengths ± ¹ / 2 styles, laminae 0. Disc florets 5–20. Cypselae pale tan, 0.5–1 mm, glabrous or sparsely strigillose (hairs 0.05–0.1 mm), sometimes stipitate- or sessile-glandular; pappi fragile or readily falling, of 10–30 whitish bristles in 1 series, (2.5–)3.5–4 mm. 2n = 18.

Flowering year round, mostly fall. Stream banks, roadsides, other disturbed sites, clays or sands, often alkaline soils; -60–1800 m; Ariz., Calif., Colo., Nev., N.Mex., Tex., Utah; Mexico.

J. M. Kingsbury (1964) reported Laënnecia coulteri (as Conyza coulteri) to be toxic to livestock.