Trifolium stoloniferum
Man. Bot. ed. 2, 468. 1818.
Herbs perennial, 10–20 cm, glabrous or sparsely pubescent. Stems creeping, branched, rooting at nodes. Leaves palmate, opposite or subopposite on erect stems; stipules lanceolate (on prostrate stems) or ovate (on erect stems), 1–2 cm, margins entire or shallowly serrate, apex acuminate; petioles 6–15 cm on prostrate stems, 0.5–4 cm on erect stems; petiolules 1 mm; leaflets 3, blades broadly ovate or obcordate, 1–2 × 0.5–2.5 cm, base broadly cuneate to rounded, veins fine, margins serrate, apex emarginate or rounded, surfaces glabrous. Peduncles 2–7 cm. Inflorescences terminal, single or paired at tip of upright stem, 15–30-flowered, globose, 2–3.5 × 2–3.5 cm; involucres absent. Pedicels elongated and strongly reflexed in fruit, 2–5 mm; bracteoles lanceolate, 2 mm. Flowers 9–15 mm; calyx campanulate, 4–7 mm, glabrous or sparsely pubescent, veins 10, tube 1.3–3.3 mm, lobes subequal, subulate, orifice open; corolla white, veins often pinkish, 8–14 mm, banner ovate or oblong, 8–14 × 4–5 mm, apex rounded or emarginate. Legumes oblong, 2.5–3 mm. Seeds 1 or 2, tan to brown, reniform, 1.3–2 mm, smooth. 2n = 16.
Phenology: Flowering Apr–Jun.
Habitat: Grassy openings in upland woods.
Elevation: 150–900 m.
Distribution
Ind., Ky., Mo., Ohio, Pa., W.Va.
Discussion
Trifolium stoloniferum was thought to be extinct but was rediscovered in the early 1980s (R. L. Bartgis 1985). It is now known from extant populations scattered throughout much of its original range, in five of the original eight states in which it was found historically (D. J. Crawford et al. 1998); it was discovered in Greene County, Pennsylvania, in 2017, but appears to be extirpated in Arkansas, Illinois, and Kansas. R. J. Hickey et al. (1991) examined genetic diversity of T. stoloniferum populations using allozymes and found low diversity, with some populations appearing genetically uniform. Molecular studies using RAPDs (Crawford et al.) indicated somewhat higher genetic diversity, even in relatively small populations.
Trifolium stoloniferum is in the Center for Plant Conservation’s National Collection of Endangered Plants.
Selected References
None.