Vines perennial, with slender taproot. Stems terete, often lignescent at base, from subter­ranean, branched caudex, sometimes with adventitious roots. Leaves: leaflet blades usually ovate-lanceolate, sometimes narrowly lanceolate, margins entire or shal­lowly, rarely deeply, lobed, sinus 0–1(–6) mm, lateral leaflets 1.5–4.2 × 0.3–2.7 cm, terminal leaflet (1.5–)2–4(–7) × 0.2–2.2(–3) cm, surfaces strigose. Peduncles stout, lignescent, (4.4–)6–30 cm, 0.8–1.3 mm diam. Inflorescences with (1 or)2–6(–11) flower-bearing nodes. Flowers: bracteoles 0.8–2.4 mm, shorter than calyx tube; calyx tube (1.4–)2–4 mm, lobes 1–2.5(–3) mm; banner pink, 7.3–15 mm; wings pinkish, 7–12 mm; keel 8–13 mm, beak prominent, erect, slightly curved, 1.5–2 mm diam., closely positioned to face of banner petal, protruding well above wings. Legumes subcylindric, laterally compressed, 3–7 × 0.2–0.6 cm, glabrate or sparsely strigose. Seeds 5–10, sometimes faintly mottled, with cellular or waxy cover­ing. 2n = 22.

Phenology: Flowering Jul–Sep.
Habitat: Fields, meadows, rarely in wood­lands.
Elevation: 0–1500 m.

Distribution

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Ala., Ark., Conn., Del., D.C., Fla., Ga., Ill., Ind., Iowa, Kans., Ky., La., Md., Mass., Mich., Miss., Mo., N.J., N.Mex., N.Y., Okla., Pa., R.I., S.C., S.Dak., Tenn., Tex., Va., W.Va., Wis.

Discussion

Strophostyles umbellata is highly variable in leaflet shape, from narrowly lanceolate like those of S. leiosperma to ovate-lanceolate like those of S. helvola. It is best distinguished by its prominent keel beak, which has a thick base, a curved tip, and is held close to the banner face.

Selected References

None.

Lower Taxa

None.