Arizona snakeweed

Greenella arizonica A. Gray, Proc. Amer. Acad. Arts 16: 81. 1880; Xanthocephalum arizonicum (A. Gray) Shinners

Annuals, 12–30 cm . Stems glabrous. Leaves: basal sometimes persistent, proximal usually absent at flowering; cauline blades 1-nerved, narrowly elliptic-oblanceolate to elliptic-lanceolate, 1–2 mm wide, reduced distally. Heads borne singly or in loose, open arrays. Involucres campanulate, 4–7 mm diam. Phyllary apices flat. Ray florets 8–15; corollas white, drying light yellow or reddish, 6–7.5 mm. Disc florets (16–)20–30(–40). Cypselae 0.9–1.6 mm, faces without oil cavities, densely strigoso-sericeous (hair apices prominently bulbous-capitate); pappi coroniform or of 1 series of basally connate scales 0.1–0.3 mm (obscured by cypsela indument). 2n = 8.

Flowering (Feb–)Mar–May. Sandy or sandy-rocky plains or washes; 200–1300 m; Ariz.; Mexico (Sonora).