Oenothera hilgardii Greene, Bull. Torrey Bot. Club 10: 41. 1883 (as hilgardi); Camissonia hilgardii (Greene) P. H. Raven; Holmgrenia hilgardii (Greene) W. L. Wagner & Hoch; O. andina Nuttall var. hilgardii (Greene) Munz; Sphaerostigma andinum (Nuttall) Walpers var. hilgardii (Greene) A. Nelson; S. hilgardii (Greene) Small

Herbs finely strigillose, more densely so distally, espe­cially on ovary. Stems erect to ascending, capillary, 1–15 cm. Leaves linear to linear-oblanceolate, 1–3 × 0.1–0.3 cm. Flowers opening near sunrise; floral tube 1.5–2 mm; sepals 2–3 mm; petals 2.5–5 mm; epi­sepalous fila­ments 2–4 mm, epipetalous filaments 1.5–2.8 mm, sometimes epipetalous stamens absent, anthers of longer stamens 0.7–0.8 mm, those of shorter ones 0.5–0.6 mm; style 4.5–6 mm, sparsely pubescent near base, stigma 0.7–0.8 mm diam., surrounded by anthers at anthesis. Capsules ascending, strongly flattened from unequal width of valves, 5–10 × 1–1.3 mm. Seeds 0.7–1.3 × 0.3–0.4 mm. 2n = 14.

Flowering May–Jul. Sandy or clay soil, in sagebrush scrub; 0–500 m; Oreg., Wash.

Neoholmgrenia hilgardii is probably self-compatible but outcrossing. The species occasionally grows sympatrically with N. andina (P. H. Raven 1969). It is known from Chelan, Douglas, Grant, Kittitas, Okanagan, and Yakima counties, Washington. The species was collected twice along the lower Columbia River, at Bingen, Klickitat County, Washington, and Hayden Island, Multnomah County, Oregon.