Herbs annual, 10–80 cm, gla­brous or appressed-pubescent. Stems prostrate to ascending, branched. Leaves palmate; stip­ules ovate, 0.5–3 cm, margins entire or slightly toothed, ciliate, apex acute to acuminate; petiole 1–20 cm; petiolules 1 mm; leaflets 3, blades broadly obcor­date, 0.8–2.8 × 1–3 cm, base cuneate, veins delicate, widely spaced, margins mostly entire, slightly dentate distally, apex emarginate, surfaces appressed-sericeous. Peduncles 2–6.5 cm. Inflorescences axillary, elongate and reflexed, pushing into substrate after anthesis, fertile flowers 2–7, sterile flowers 0–80, globose or cylindric, 0.5–1.5 × 0.8–1.5 cm; involucres absent. Pedicels reflexed after anthesis, 0.2–0.4 mm; bracteoles absent. Flowers: fertile ones 7–15 mm; calyx tubular, 5–6 mm, glabrous or hairy, veins indistinct, tube 3–4 mm, lobes subequal, pubescent or glabrous, spreading, orifice open; corolla white, pink, or pink-striped, 7–10 mm, banner ovate-elliptic, 7–10 × 1.5–2 mm, apex rounded; sterile flowers 4–7 mm; calyx teeth linear; corolla absent. Legumes subterranean, obovoid, 3–4 mm. Seeds 1, pur­plish black, ellipsoid, 2.6–3 mm, smooth, dull. 2n = 16.

Phenology: Flowering Mar–May.
Habitat: Open, disturbed sandy soils.
Elevation: 0–1000 m.

Distribution

• Generated Map
• Legacy Map

Introduced; B.C., Calif., Ga., La., Mass., Miss., N.J., N.C., Oreg., S.C., Wash., w Europe, w Asia, n Africa, introduced also in s South America, s Africa, Pacific Islands (Hawaii, New Zealand), Australia.

Discussion

Trifolium subterraneum was first introduced by the USDA about 1921 as a pasture crop; it is utilized as such in the western and southern United States (W. S. McGuire 1985). Inflorescences of T. subterraneum consist of intermixed sterile and fertile flowers; after fetilization, the inflorescence is pushed underground, where the fruits develop.

Selected References

None.

Lower Taxa

None.