Roundleaf Snakeweed

Annuals, 20–50 cm. Stems minutely, prominently, often sparsely, papillate-scabrous (hairs triangular or deltate to lanceolate, less than 0.1 mm). Leaves: proximal usually absent at flowering; cauline blades 1-nerved, linear, 0.5–1.2 mm wide, little reduced distally. Heads in loose arrays. Involucres campanulate, 2.5–5 mm diam. Phyllary apices flat. Ray florets 10–15; corollas yellow, 3–5.5 mm. Disc florets 18–37. Cypselae 0.9–1.2(–1.4) mm, faces without oil cavities, densely strigoso-sericeous in rows (hairs appressed to spreading, apices clavate); pappi of 1 series of narrowly triangular or narrowly oblong scales 0.2–1 mm (distinct or basally connate ¹ / 4 – ³ / 4 their lengths, usually shorter in rays). 2n = 8 (10).

Gutierrezia eriocarpa A. Gray; Xanthocephalum sphaerocephalum (A. Gray) Shinners; Xanthocephalum sphaerocephalum var. eriocarpum (A. Gray) Shinners