Goldenrod snakeweed

Xanthocephalum petradoria S. L. Welsh & S. Goodrich, Brittonia 33: 301. 1981

Perennials, 10–40 cm. Stems minutely scabro-hirtellous. Leaves: basal persistent at flowering; cauline blades mostly 3- or 5-nerved, linear-spatulate to linear, proximal 1–3(–4) mm wide, narrower distally. Heads borne singly or (2–4) in loose arrays. Involucres broadly turbinate to obconic, 4–7 mm diam. Phyllary apices flat, ± swollen. Ray florets (4–)5–10; corollas yellow, 5–8(–10) mm. Disc florets 15–23 (bisexual and fertile or functionally staminate). Cypselae 1.5–3(–3.5) mm, faces without oil cavities, loosely strigose (hair apices acute); pappi of 1–2 series of scales (0.5–)1–2.2 mm. 2n = 8.

Flowering Aug–Oct(–Nov). Rocky ridges, crevices, and slopes, quartzite or limestone substrate, sagebrush, mountain mahogany, white fir communities; 1800–2700 m; Utah.

Gutierrezia petradoria is distinctive, especially in its herbaceous form. The basal leaves are persistent, and the relatively large ray corollas are showy.