Short-seed waterwort Short-seed waterwort

Alsinastrum brachyspermum (A. Gray) Greene; Elatine obovata (Fassett) H. Mason; E. triandra Schkuhr var. brachysperma (A. Gray) Fassett; E. triandra var. obovata Fassett; Potamopitys brachysperma (A. Gray) Kuntze

Herbs, submersed or emersed on wet substrates, 0.5–3(–5) cm. Stems ascending or prostrate, branched. Leaves reddish green; stipules lanceolate, 0.5–0.6 mm, margins dentate, apex acute; petiole (0–)1–3 mm; blade narrowly oblong to ovate, 3–8 × 1–3 mm, base cuneate to rounded, apex rounded to obtuse. Pedicels 0–0.4 mm, erect. Flowers: sepals (2–)3, equal, oblong-ovate, 1.1–1.3 × 0.3 mm; petals 3, pinkish, elliptic or ovate, 1–1.5 × 0.5 mm; stamens 3; styles 3. Capsules globose, 3-locular, 1.1–1.7 mm diam. Seeds (6–)10–15 per locule, oblong, straight or curved to 30°, 0.3–0.5 × 0.1–0.3 mm; pits ± round, length 1–2 times width, in 6(–8) rows, (9–)14–17 per row.

Flowering summer–early fall. Muddy shores, often of ponds or reservoirs; 0–1500(–2200) m; B.C.; Ala., Ariz., Calif., Ga., Ill., La., Mont., Nebr., Nev., N.Mex., Ohio, Okla., Oreg., Tex., Wash., Wyo.; Mexico (Baja California); South America (Argentina).