Howell’s ivesia

Ivesia alpicola Rydberg ex Howell, Fl. N.W. Amer., 182. 1898; Horkelia gordonii Hooker var. alpicola (Rydberg ex Howell) Rydberg

Stems usually greenish, rarely reddish, usually ascending to erect, sometimes decumbent, 0.3–2 dm, not or sparsely hirsute to villous, glandular-puberulent or -pubescent. Basal leaves 2–8(–10) × 0.5–1(–1.5) cm; leaflets 2–5(–9) mm, hirsute to pilose, rarely minutely glandular at least marginally. Inflorescences 5–25-flowered, usually simple, 1–3(–4) cm diam., glomerules usually 1, ± capitate. Flowers 5–9 mm diam.; epicalyx bractlets (1.5–)2–3(–4) mm; hypanthium (2–)2.5–3.5(–4) × 2.5–4 mm; sepals 2–4(–5) mm, acute; anthers rarely red-margined.

Flowering summer. Dry grassy areas on talus, or gravelly or rocky slopes and ridges, in subalpine and alpine montane conifer woodlands, alpine tundra; 2100–3300 m; Calif., Idaho, Mont., Oreg., Wash.

P. A. Rydberg (1898) used var. alpicola (as Horkelia gordonii var. alpicola) for compact, high-elevation plants throughout the range of Ivesia gordonii. As circumscribed here, var. alpicola is restricted to plants occurring disjunctly in an arc around the northwestern part of the species range. Populations occur in the northern Coast Ranges and central Sierra Nevada of California, sporadically to Mount Adams and the Wenatchee Mountains in Washington, and from there to the mountains of central Idaho and the Bitterroot Range of Montana. The variety is also disjunct on the Owyhee Mountains of southwestern Idaho.

Plants of var. alpicola average shorter than those of var. gordonii, which occurs farther east and south. In var. alpicola, stems with only glandular indumentum are common; such stems are rare in var. gordonii. Unlike those of var. gordonii, the leaflets of var. alpicola are frequently glandular with only marginal hairs.