Sonoran Pricklyleaf

Annuals, green, 3–12+ cm, glabrous. Stems spreading to ascending or erect. Leaves alternate; blades 10–15 mm overall, lobed, lobes (3–)5–9, linear to filiform. Peduncles 1–5+ mm, glabrous. Calyculi 0, or of 1–2 subulate bractlets, lengths less than ¹/2 phyllaries. Involucres obconic to campanulate, 5–6.5 mm. Phyllaries 8–16, margins of outer distinct less than ¹/2 their lengths, abaxial faces glabrous. Ray florets 9–12; corollas white to pale yellow, laminae 3–4 × 1–3.5 mm. Disc florets ca. 25; corollas pale yellow, 3–4.5 mm. Cypselae 2.5–3 mm; pappi of 10–15 scales (each comprising 5–9 basally connate bristles) 1–2.5 mm. 2n = 16.

Hymenatherum concinnum A. Gray in A. Gray et al., Syn. Fl. N. Amer. 1(2): 446. 1884; Dyssodia concinna (A. Gray) B. L. Robinson

Boeberastrum concinnum (A. Gray) Rydberg
Hymenatherum concinnum A. Gray, Syn. Fl. N. Am. I 2 : 446. 1884. Dyssodia concinna B. L. Robinson, Proc Am. Acad. 49: 507. 1913.
A depressed annual; stem branched at the base; branches spreading, glabrous glaucescent; leaves alternate, fleshy, 1-2 cm. long, pinnately parted into linear obtuse divisions; heads subsessile and clustered at the summit of the leafy branches; involucre subhemispheric or shortcampanulate, about 6 mm. high and fully as broad; bracts 12-14, united fully half their length, with 2 rows of rounded glands; free portion ovate, scarious-margined; ray-flowers 10-12; ligules oblong, white, 4-5 mm. long; disk-corollas yellow, about 5 mm. long, glabrous; tube about equaling the trumpet-shaped throat; achenes clavate, 3.5 mm. long, angled, sparingly hairy on the angles; pappus 2.5 mm. long; squamellae 10, dissected into 5-7 bristles.
Type locality: [Near Tucson], Arizona. Distribution: Arizona.