Trifolium hydrophilum
Man. Bot. San Francisco, 100. 1894.
Herbs annual, 15–55 cm, glabrous. Stems erect, branched. Leaves palmate; stipules ovate-oblong to lanceolate, 0.4–1.3 cm, sheathing proximally, margins entire or serrate, apex acuminate; petiole 3–9 cm; petiolules 0.5 mm; leaflets 3, blades obovate to oblanceolate, 1.2–3 × 0.3–1.4 cm, base cuneate, veins fine, margins serrate, apex rounded or truncate, surfaces glabrous. Peduncles 3.5–6 cm. Inflorescences axillary or terminal, 5–15-flowered, ellipsoid, 1–1.8 × 1.3–1.5 cm; involucres flattened, 3–4 mm, shallowly incised, lobes 5–8, elliptic, apex rounded to truncate and irregularly erose, not split. Pedicels erect, 1 mm; bracteoles broadly ovate, to 0.5 mm. Flowers 7–11 mm; calyx campanulate-tubular, 2.5–5 mm, glabrous, veins 5, tube 1–2.5 mm, lobes unequal, lanceolate-subulate, orifice open; corolla reddish purple, 7–9 mm, inflated in fruit, banner oblong, 7–9 × 3–4 mm, apex rounded, retuse. Legumes stipitate, ovate-oblong, 4 mm. Seeds 1 or 2, red-brown, ovoid-ellipsoid, 2 mm, smooth or papillate.
Phenology: Flowering Apr–May.
Habitat: Wet, alkaline soils, salt marshes.
Elevation: 0–300 m.
Distribution
Calif.
Discussion
Trifolium hydrophilum is closely allied to T. depauperatum and is restricted to the Sacramento Valley, northwestern San Joaquin Valley, and central-western California; it grows in moist areas, sometimes in standing water (M. A. Vincent and D. Isely 2012).
Selected References
None.