Herbs perennial, 20–50 cm, gla­brous; rhizomes elongate, slen­der, roots tuberous. Stems erect, sparsely branched. Leaves pal­mate; stipules lanceolate, 0.8–1.5 cm, margins entire or slightly lacerate, apex acuminate; peti­ole 1.6–2.4 cm; petiolules 0.5 mm; leaflets 3, blades obovate, oblanceolate, or elliptic, 0.8–3 × 0.5–0.7 cm, base cuneate, veins fine or thickened distally, margins finely serrulate, apex acute, mucronate, or retuse, surfaces glabrous. Peduncles 2.8–3.4 cm. Inflorescences usually terminal, sometimes axillary, 30–50-flowered, subglobose, 1.2–1.8 × 1.5–2 cm; involucres shallowly bowl-shaped, 18–22 mm, deeply incised, lobes slender, irregular or bifurcate. Pedicels straight, 0.5–0.8 mm; bracteoles linear, 1–2 mm. Flowers 10–13 mm; calyx tubular, 0.5–0.6 mm, glabrous, veins 10, tube 2 mm, lobes ± equal, 3–4 mm, orifice open; corolla white to purple, 9–12 mm, banner oblong, 7–12 × 2–3 mm, apex retuse. Legumes oblong, 2–4 mm. Seeds 2–4, brown, subglobose or mitten-shaped, 1.5 mm, smooth.

Phenology: Flowering Jun–Jul.
Habitat: Wet meadows, grassy hillsides.
Elevation: 1000–1500 m.

Distribution

• Generated Map
• Legacy Map

Calif., Oreg.

Discussion

Trifolium siskiyouense is known from Shasta and Siskiyou counties, California, and Douglas, Jackson, and Josephine counties, Oregon. It is difficult to distin­guish from T. wormskioldii without underground parts showing the tubers, but can be separated from the latter by deeply cut involucral segments, long-lobed, slender calyces, and the combination of long wing petals and short keel petals (J. M. Gillett 1980).

Selected References

None.

Lower Taxa

None.