Gutierrezia petradoria (S.L. Welsh & Goodrich) S.L. Welsh
Family: Asteraceae
San Pedro Snakeweed
[Xanthocephalum petradoria S.L. Welsh & Goodrich]
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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.