Spiny or cushion or showy milkwort

Polygala subspinosa S. Watson, Amer. Naturalist 7: 299. 1873

Subshrubs or shrubs, multi-stemmed, 0.5–2.5(–6) dm. Stems prostrate to erect, sometimes glaucous, at least when young, glabrous or pubescent, hairs spreading to slightly incurved. Leaves subsessile to petiolate, petiole to 1(–2) mm; blade obovate or elliptic, 4–31 × 0.8–11 mm, base cuneate, apex rounded or acute, surfaces densely to sparsely pubescent or subglabrous, hairs spreading to slightly incurved. Racemes terminal, sometimes reduced to (1 or)2–few flowers, 3–12.5 cm; rachis thorn-tipped; peduncle 0.1–0.5 cm; bracts usually deciduous, rarely persistent, elliptic, ovate, or lanceolate. Pedicels (1.5–)3.5–10(–20.5) mm, glabrous or pubescent. Flowers pink to rose, wings (and other sepals) sometimes light green, distal keel yellow or green, (6–)8–12(–13) mm; sepals deciduous, ovate, elliptic, or lanceolate, 2–7.2 mm, glabrous or pubescent; wings obovate to elliptic-obovate, (5–)7–11.5(–12.2) × (2.3–)3–5.2(–5.9) mm, glabrous or pubescent; keel (5.4–)6.2–10.5 mm, sac glabrous, beak oblong, 1–3 × 0.9–1.5 mm, glabrous. Capsules ellipsoid to obovoid, 4.3–8.8(–10) × 3.7–7.3 mm, base cuneate to rounded, margins with narrow, entire or slightly erose wing, glabrous or pubescent. Seeds 3.3–4.9 mm, ± evenly and moderately densely pubescent, occasionally with glabrate patches; aril 1.2–3.1 mm, lobes to 1/2 length of seed. 2n = 18, 36.

Flowering spring–mid summer. Gravelly soils derived from limestone, shale, lava, or tuff, or crevices of soft calcareous rocks on eroded hills, open slopes and flats, in desert scrub, open pinyon-juniper woodlands, mountain brush, ponderosa pine woodlands; 1300–2400 m; Ariz., Calif., Colo., Nev., N.Mex., Utah.