Sierra Valley ivesia

Stems ascending to erect. Flowers (20–)30–250, usually more than 10 per glomerule, 5–10 mm diam.; hypanthium 2–3(–4) mm diam.; petals oblanceolate, 2–3 mm, shorter than sepals; filaments 1–1.5(–2) mm; styles 2–3 mm. 2n = 28.

Flowering summer. Dry meadows, edges of seeps, slopes, and flats, on vernally saturated volcanic soil, in sagebrush and grass communities, conifer woodlands; of conservation concern; 1300–2300 m; Calif., Nev.

Variety aperta is most abundant in Sierra Valley and its drainages in Plumas and Sierra counties, California, barely extending into Lassen County. Disjunct populations occur in the Carson Range in southern Washoe County and the Virginia Range of Storey County, Nevada.

The chromosome count given here is based on a collection originally identified as Ivesia sericoleuca (D. D. Keck & A. Gustafsson 4901).