Vasey’s rock daisy

Perennials or subshrubs, (10–)15–75 cm (in soil, tap roots fleshy, stems erect or spreading); glandular-pubescent. Leaves: petioles 10–35 mm; blades usually palmately 3-lobed or ± cruciform, 6–35 × 10–50 mm, lobes usually again ternately dissected, cleft, or parted. Heads borne singly or (2–3) in corymbiform arrays, 8–10 × 10–13 mm. Peduncles 10–80 mm. Involucres campanulate to hemispheric. Phyllaries 20–30, oblanceolate or lanceolate to linear-lanceolate, 6–7 × 1–2 mm, apices usually acute, sometimes short-attenuate. Ray florets 12–18; corollas yellow, laminae oblong, 4–10 × 2–4 mm. Disc florets 50–100; corollas yellow, tubes 1.2–1.5 mm, throats tubular to broadly tubular, 2.2–3 mm, lobes 0.4–0.6 mm. Cypselae linear-elliptic to narrowly oblanceolate, (2–)3–4 mm, margins usually prominently calloused, sometimes thin, usually densely ciliate, sometimes short-hairy; pappi 0 or of 1(–2) retrorsely or erectly barbellate (at least near tips) bristles 1–4 mm plus crowns of hyaline, laciniate scales. 2n = 34.

Flowering year around. Desert soils, especially gypsiferous clays; 700–1800 m; Tex.; Mexico (Chihuahua, Coahuila).

Perityle vaseyi is always found growing in soil, often on roadsides and in road cuts in the southwestern Big Bend area. The more deeply dissected leaves, shorter pappus bristles with barbellate tips, and broader phyllaries help distinguish it from the soil-growing form of P. parryi.