Trifolium amphianthum
Fl. N. Amer. 1: 316. 1838.
Herbs perennial, 10–25 cm, glabrous or glabrate. Stems creeping, branched, rooting at nodes. Leaves palmate; stipules ovate-lanceolate, 0.5–1 cm, margins entire, apex acute to acuminate; petiole 3–10 cm; petiolules 0.5–1 mm; leaflets 3, blades obcordate, 0.5–1.8 × 0.5–1.5 cm, base cuneate, veins thickened, margins entire or denticulate distally, apex usually deeply emarginate, rarely rounded, surfaces glabrous. Peduncles: chasmogamous 6–8 cm, cleistogamous ± sessile. Inflorescences axillary, 5–20-flowered, globose, 1–2.2 × 1–20 cm, chasmogamous erect, cleistogamous becoming subterranean; involucres formed of distinct, narrowly lanceolate bracts, 2.5–3.5 mm. Pedicels reflexed in fruit, cleistogamous pushing fruit underground, chasmogamous 1–8 mm, cleistogamous 4–20 mm; bracteoles lanceolate, 2–4 mm. Flowers: chasmogamous 8–11 mm, cleistogamous 4–5 mm; calyx campanulate, 3–5 mm, slightly pilose, veins 10, tube 1.5–2 mm, lobes subequal, adaxial pair connate proximally, sometimes nearly entire length, narrowly triangular-subulate, orifice open; corolla magenta or pink, 7.5–11 mm, banner broadly obovate-elliptic, 5–10 × 5–8 mm, apex rounded, emarginate. Legumes stipitate, chasmogamous ellipsoid, cleistogamous ovoid-globose, chasmogamous longitudinally dehiscent, 3–6 mm, cleistogamous indehiscent, 3–6 mm. Seeds 2–6 (chasmogamous), 1–3 (cleistogamous), tan, mitten-shaped, 1.2–1.5 mm, smooth. 2n = 16, 32.
Phenology: Flowering Mar–Jun.
Habitat: Sandy soils, prairies.
Elevation: 0–200 m.
Distribution
La., Tex.
Discussion
Trifolium amphianthum ranges in east-central Texas from Aransas County northward to Denton County, and eastward to San Augustine and Shelby counties; it is also recorded from Natchitoches and Rapides parishes in Louisiana. Trifolium amphianthum was collected once in Arkansas, but the specimen may have been from cultivation.
The name Trifolium polymorphum Poiret applies to plants found in Argentina, Brazil, Paraguay, and Uruguay and has been misapplied to this North American endemic, as was done by M. Zohary and D. Heller (1984). Trifolium amphianthum is distinguished from T. polymorphum by its much larger leaves and flowers and essentially glabrous leaves and peduncles.
Selected References
None.