serpentine groundsel

Packera hesperia is a perennial with fibrous roots and a single herbaceous stem 7–15 cm tall, which can be either smooth or sparsely covered by woolly hairs. The basal leaves are 1–3 cm long and 0.5–2 cm wide, petiolate with tapering bases, and have either smooth or toothed margins. Cauline leaves are much smaller, have smooth edges, and clasp the stem.

At the end of the stem, there is a corymb bearing 1–4 flowering heads held on densely-woolly penduncles. Both the phyllaries (whorls of green bracts forming a cup-like structure that holds the flower) and the calyculi (bracts subtending the phyllaries) are green with red tinges or tips. The phyllaries are densely-woolly near their bases. Flowering occurs from mid-April to mid-June. The flower is composite, with 8–13 yellow ray florets 6–10 mm long and 30–50 disc florets. The cypselae (dry fruit holding a single seed) are 1.5–2 mm long. The pappi, which act as parachutes for the seeds during wind dispersal, are 5–6 mm long.

Packera hesperia is endemic to the Siskiyou Mountains, where it grows at elevations of 500–2500 m. There are at least 5,000 individuals in Josephine and Curry Counties in southwestern Oregon, spread across at least 45 populations. In California, there are 4 known populations, all in Del Norte County. It grows in open woodlands on serpentine soils. Associated species commonly found growing with P. hesperia include the serpentine endemics Pinus jeffreyi and Arctostaphylos viscida.