Annuals; (terrestrial or of wet habitat, not submerged); glabrous throughout. Stems (several-branched from base), prostrate to decumbent, branched distally, 0.7–3.5 (–4) dm. Basal leaves not rosulate; blade margins pinnatifid. Cauline leaves shortly petiolate, or (distal) sessile; blade oblong to oblanceolate or lanceolate, (lateral lobes linear, oblong to ovate, or obovate), 2–9 (–11) cm × 7–20 (–30) mm, (lateral lobes smaller than terminal), base not auriculate, margins pinnatifid, or (lateral lobes) entire, dentate, or sinuate. Racemes elongated. Fruiting pedicels ascending to divaricate, (1–) 1.5–3.2 (–4.2) mm, straight. Flowers: sepals ascending, oblong, 0.7–1.3 × 0.4–0.7 mm; petals yellow, oblong to oblanceolate or spatulate, 0.5–0.8 × 0.1–0.3 mm; median filaments 0.8–1.2 mm; anthers ovate, 0.1–0.2 mm. Fruits siliques or silicles, curved-ascending, lanceolate to narrowly ovoid or oblong-lanceolate, 3–7 (–9) × (0.8–) 1–1.7 (–2) mm (often slightly constricted at middle); valves papillate; ovules 20–80 per ovary; style (0.2–) 0.5–1 mm. Seeds biseriate, reddish-brown, cordiform, 0.5–0.7 mm, colliculate.

Phenology: Flowering Jun–Oct.
Habitat: Shores of lakes and ponds, mud flats, marshes, sand bars, moist grounds, streamsides
Elevation: 1300-3000 m

Distribution

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Alta., B.C., Sask., Calif., Colo., Idaho, Mo., Mont., Nebr., Nev., N.Mex., N.Dak., Oreg., S.Dak., Tex., Utah, Wash., Wyo., Mexico (Baja California), Mexico (Chihuahua)

Discussion

Selected References

None.

Lower Taxa

None.

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