Trifolium macrocephalum
Trifolium stoloniferum
big-head clover, large-head clover
running buffalo clover
erect or ascending, branched.
creeping, branched, rooting at nodes.
palmate;
stipules ovate, obovate, or oblong, 1–3 cm, margins entire, irregularly lobed, or serrate, apex acute or acuminate;
petiole 1–14 cm;
petiolules 0.9–1.2 mm;
leaflets (5–)7–9, blades broadly to narrowly obovate, often folded, 1–2.7 × 0.4–1.1 cm, base cuneate, veins thickened, especially distally, margins serrulate, apex rounded or truncate, apiculate, surfaces villous abaxially, sparsely villous to glabrate adaxially.
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.
terminal, 20–32-flowered, globose or ovoid-ellipsoid, 2.5–8 × 3–7 cm;
involucres absent.
terminal, single or paired at tip of upright stem, 15–30-flowered, globose, 2–3.5 × 2–3.5 cm;
involucres absent.
2–8 cm.
2–7 cm.
erect, 1–1.5 mm;
bracteoles broadly ovate, membranous, to 0.5 mm, truncate.
elongated and strongly reflexed in fruit, 2–5 mm;
bracteoles lanceolate, 2 mm.
20–30 mm;
calyx campanulate, 10–22 mm, villous, veins 10–15, tube 2.5–4 mm, lobes subequal, subulate, plumose, orifice open;
corolla white, creamy white, or pinkish, keel petals deep pink, 20–28 mm, banner ovate or oblong, 20–28 × 10–13 mm, apex rounded or slightly emarginate.
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.
ovoid, 4–5 mm.
oblong, 2.5–3 mm.
1 or 2, yellow or reddish, mitten-shaped to ellipsoid, 2.5–3 mm, smooth.
1 or 2, tan to brown, reniform, 1.3–2 mm, smooth.
= 32, 48.
= 16.
Trifolium macrocephalum
Trifolium stoloniferum
Trifolium macrocephalum has the largest inflorescences of any clover. Trifolium megacephalum Nuttall (1818) is an illegitimate replacement name for Lupinaster macrocephalum Pursh.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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