Trifolium nanum
Ann. Lyceum Nat. Hist. New York 1: 35, plate 3, fig. 4. 1824.
Herbs perennial, 4–10 cm, glabrous. Stems cespitose, matted, acaulescent. Leaves palmate; stipules ovate-lanceolate, 1–2 cm, margins entire, apex acuminate, sometimes forked; petiole 0.3–2.5 cm; petiolules to 0.2 mm; leaflets 3, blades oblanceolate or obovate, 0.3–1.2 × 0.1–0.5 cm, base cuneate, veins ± thickened, margins toothed, apex acute or acuminate, surfaces glabrous. Peduncles 0.5–3 cm. Inflorescences terminal or axillary, 1–4-flowered, umbellate, 1.5–2 × 0.5–1 cm, rachis not prolonged beyond flowers; involucres a narrow, membranous, dentate rim, 1 mm. Pedicels erect, 1 mm; bracteoles cuplike, membranous, 0.5–1 mm. Flowers 15–20 mm; calyx campanulate, 4–7 mm, glabrous, veins 5–10, tube 3–4 mm, lobes equal, triangular-acuminate, orifice open; corolla purple or violet, 15–20 mm, banner oblong, 15–20 × 7–9 mm, apex rounded, slightly retuse. Legumes oblanceoloid, 9–11 mm. Seeds 4–6, tan or brown, mitten-shaped, 2–2.2 mm, smooth, dull. 2n = 16.
Phenology: Flowering Jun–Aug.
Habitat: Alpine slopes, tundra.
Elevation: 2600–4500 m.
Distribution
Colo., Mont., N.Mex., Utah, Wyo.
Discussion
Trifolium nanum is abundant in alpine tundra areas from Montana through Wyoming and Utah into Colorado (where it is most common) and northern New Mexico; populations are morphologically variable with regard to leaf size and petiole length, and this variability appears to be related to water availability (J. M. Gillett 1965).
Selected References
None.