Spreading dogbane, Apocyn à feuilles d’androsème

Apocynum androsaemifolium var. incanum A. de Candolle; A. androsaemifolium var. intermedium Woodson

Herbs 2–10 dm. Stems glabrous or eglandular-pubescent. Leaves drooping or spreading; petiole 3–5 mm, glabrous or pubes­cent; blade ovate to oblong-lanceolate, (1–)3–6(–9) × (1–)1.5–3(–5) cm, mostly less than 2 times as long as wide, membranous, base rounded to cuneate, margins weakly to strongly revolute, apex acute to rounded, usually apiculate, surfaces glabrous or densely eglandular-pubescent abaxially, glabrous or sparsely eglandular-pubescent adaxially. Inflorescences usually exceeding foliage; peduncle 1–5 cm, glabrous or sparsely pubescent. Pedicels 1.5–7 mm, glabrous or sparsely pubescent. Flowers: calyx lobes broadly to narrowly triangular-ovate to lanceolate, 1.5–2.5 × 0.5–1 mm, glabrous or with a few scattered hairs; corolla pink or white with pink veins, glabrous abaxially and adaxially, tube 4–5 × 3–4 mm, at least 3 times as long as calyx lobes, lobes spreading or recurved, triangular-ovate, 1.5–3 × 0.7–1.2 mm. Follicles 60–150 × 2–3 mm. Seeds 1.5–2 × 0.3–0.5 mm. 2n = 16, 22.

Flowering spring–summer; fruiting summer–fall. Hardwood and coniferous forests and woodlands, clearings, mountain canyons, river terraces, old fields, pastures, roadsides; 10–3000 m; Alta., B.C., Man., N.B., Nfld. and Labr., N.W.T., N.S., Ont., P.E.I., Que., Sask., Yukon; Ala., Alaska, Ariz., Ark., Calif., Colo., Conn., Del., D.C., Ga., Idaho, Ill., Ind., Iowa, Ky., Maine, Md., Mass., Mich., Minn., Mo., Mont., Nebr., Nev., N.H., N.J., N.Mex., N.Y., N.C., N.Dak., Ohio, Okla., Oreg., Pa., R.I., S.C., S.Dak., Tenn., Tex., Utah, Vt., Va., Wash., W.Va., Wis., Wyo.; Mexico (Chihuahua, Coahuila).

R. E. Woodson Jr. (1930) recognized three varieties of Apocynum androsaemifolium based primarily on minor differences in corolla morphology and leaf pubescence; these varieties are not recognized here.