Herbs annual, 5–50 cm, gla­brous. Stems erect, branched. Leaves palmate; stipules ovate to lanceolate, 0.6–1.2 cm, mar­gins entire, toothed, or lacerate, apex acute or aristate; petiole 1–10 cm; petiolules to 0.5 mm; leaflets 3, blades obovate, ellip­tic, or oblan­ceolate, 0.5–2.5 × 0.3–1.5 cm, base cuneate, veins prominent, green, mar­gins finely toothed, apex rounded, blunt, or retuse, sur­faces glabrous. Peduncles 1–8 cm. Inflorescences axil­lary or terminal, 1–35-flowered, subglobose or ovoid, 0.5–1.8 × 0.5–2 cm; involucres broadly bowl-shaped, 4–22 mm, shallowly incised, lobes 3–15, toothed, broad, acute. Pedicels straight, 0.1–0.2 mm; bracteoles absent. Flowers 7–15 mm; calyx campanulate, inflated in fruit, 6–13 mm, glabrous, veins 13–20, tube 3–7 mm, lobes unequal, strongly oblique, broadly triangular, apex setaceous, adaxial unbranched, abaxial and lateral conspicuously 2- or 3-fid, segments glabrous, sometimes flattened, orifice open; corolla usually creamy white or rose to pink, sometimes whitish with pinkish tips, 6–13 mm, banner obovate or elliptic, proximally inflated in fruit, distally narrowed into twisted tip, 6–13 × 3–6 mm, apex rounded to broadly acute. Legumes ellipsoid, 2.5–3 mm. Seeds 1 or 2, yellow-brown, ovoid, 0.4–0.6 mm, smooth. 2n = 16.

Phenology: Flowering Apr–Oct.
Habitat: Wet meadows, roadsides, fields.
Elevation: 0–2700 m.

Distribution

• Generated Map
• Legacy Map

B.C., Yukon, Alaska, Calif., Idaho, Mont., Nev., Oreg., Wash., introduced in Asia (China, Japan).

Discussion

Trifolium cyathiferum may be of hybrid origin; phylogenetic studies indicate it has the same trnL intron sequence as T. buckwestiorum, T. polyodon, and T. variegatum and nrDNA and combined analyses place it in a clade with other species (T. barbigerum, T. fucatum, T. jokerstii, and T. physanthum Hooker & Arnott) that have inflated fruiting corollas (N. W. Ellison et al. 2006).

The single record of Trifolium cyathiferum labeled as from Utah is likely mislabeled (S. L. Welsh et al. 2008). Populations in Yukon may be introductions.

Selected References

None.

Lower Taxa

None.