Trifolium polyodon

Herbs annual, 10–60 cm, glabrous. Stems decumbent or ascending, branched. Leaves palmate; stipules lanceolate to ovate, 0.4–1.8 cm, margins lacerate, apex acute to acuminate; petiole 0.5–6 cm; petiolules to 1 mm; leaflets 3, blades broadly elliptic to broadly obovate, 0.4–2.5 × 0.4–1.5 cm, base cuneate, veins moderately thickened, margins dentate-serrulate, apex rounded or truncate, often retuse, surfaces glabrous. Peduncles 1–2 cm. Inflorescences axillary, 10–25-flowered, subglobose or globose, 1–1.8 × 1–1.8 cm; involucres flattened or bowl-shaped, 4–7 mm, incised 1/2 their length, when folded, not hiding flowers except proximally, lobes 5–12, dentate-lacerate, spinulose. Pedicels straight, to 1 mm; bracteoles absent. Flowers 8–10 mm; calyx campanulate-tubular, not slit between adaxial lobes, 5–7 mm, glabrous, veins 20, tube 1.9–2.4 mm, lobes unequal, 3-fid or laciniate, often appearing 7+-lobed, orifice open; corolla pink or pale purple, 8–9 mm, banner elliptic, 8–9 × 2–3 mm, apex retuse. Legumes ellipsoid, 3.5–4 mm. Seeds 2, dark brown, mottled, ovoid or reniform, 1.7–1.9 mm, smooth.

Phenology: Flowering Apr–Jun.
Habitat: Along streams, moist meadows.
Elevation: 0–150 m.

Calif.

Discussion

The taxonomic status of Trifolium polyodon, known only from Monterey County, has long been debated. W. L. Jepson (1936) considered it a variety of T. tridentatum Lindley (= T. willdenovii). The first to consider it as a variety of T. variegatum was J. S. Martin (1943), who never formally published a new combination; an invalid combination was made by M. Zohary and D. Heller (1984). D. Isely (1998) included it in his interpretation of T. variegatum as phase 5 of that species; he speculated that T. polyodon might have originated as a hybrid of T. variegatum and T. willdenovii. Molecular studies (N. W. Ellison et al. 2006) showed that T. polyodon is closely related to T. variegatum but is distinct; it also appears to be related to T. cyathiferum.

Selected References

None.

Lower Taxa