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low yellow-cress, Modoc yellow-cress, slender yellowcress, watercress, yellow cress

spreading yellow-cress, western yellow-cress

Habit Annuals; (terrestrial or of wet habitat, not submerged); glabrous throughout. Perennials; (rhizomatous or with creeping roots); sparsely to moderately pubescent, (trichomes hemispherical, vesicular).
Stems

(several-branched from base), prostrate to decumbent, branched distally, 0.7–3.5(–4) dm.

(many to few from base), decumbent or prostrate, branched distally, 1–4.2(–5) dm, (pubescent proximally).

Basal leaves

not rosulate;

blade margins pinnatifid.

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.

sessile;

blade oblong to oblanceolate or lanceolate (lateral lobes oblong or ovate), (1.5–)2.5–6.5(–9) cm × 5–18(–25) mm, base usually auriculate, rarely proximalmost not auriculate, margins pinnatifid to deeply sinuate, or (lateral lobes) dentate to sinuate or entire, (surfaces pubescent abaxially with vesicular trichomes on veins, glabrous adaxially).

Racemes

elongated.

considerably elongated.

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.

sepals ascending, oblong, 2.2–3.7(–4.5) × 1–1.8 mm;

petals yellow, oblanceolate to spatulate, (2.7–)3.2–5.3(–6) × 1.5–2.5 mm;

median filaments 3–5.5 mm;

anthers narrowly oblong, 1.2–1.7 mm.

Fruiting pedicels

ascending to divaricate, (1–)1.5–3.2(–4.2) mm, straight.

divaricate-ascending to horizontal, sigmoid or recurved, 4–12(–14.5) 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.

siliques, curved, oblong to lanceolate or linear, (4–)5–12(–16) × (1–)1.5–2.5 mm;

valves glabrous or pubescent;

ovules (30–)50–82(–98) per ovary;

style (0.8–)1–2.5(–3.5) mm.

Seeds

biseriate, reddish brown, cordiform, 0.5–0.7 mm, colliculate.

biseriate, yellow-brown, angled, cordiform, 0.7–1 mm (0.5–0.6 mm diam.), colliculate.

2n

= 16.

Rorippa tenerrima

Rorippa sinuata

Phenology Flowering Jun–Oct. Flowering Apr–Aug.
Habitat Shores of lakes and ponds, mud flats, marshes, sand bars, moist grounds, streamsides Shores of ponds and lakes, sandy banks, stream banks, fields, wet depressions, gravel banks, ditches, moist grounds
Elevation 1300-3000 m (4300-9800 ft) 0-2600 m (0-8500 ft)
Distribution
from FNA
CA; CO; ID; MO; MT; ND; NE; NM; NV; OR; SD; TX; UT; WA; WY; AB; BC; SK; Mexico (Baja California, Chihuahua)
[WildflowerSearch map]
[BONAP county map]
from FNA
AR; AZ; CA; CO; IA; ID; IL; KS; KY; LA; MN; MO; MT; ND; NE; NM; NV; OK; OR; SD; TN; TX; UT; WA; WI; WY; AB; BC; ON; SK
[WildflowerSearch map]
[BONAP county map]
Source FNA vol. 7, p. 505. FNA vol. 7, p. 504.
Parent taxa Brassicaceae > tribe Cardamineae > Rorippa Brassicaceae > tribe Cardamineae > Rorippa
Sibling taxa
R. alpina, R. amphibia, R. aquatica, R. austriaca, R. barbareifolia, R. calycina, R. columbiae, R. crystallina, R. curvipes, R. curvisiliqua, R. dubia, R. indica, R. microtitis, R. palustris, R. ramosa, R. sessiliflora, R. sinuata, R. sphaerocarpa, R. subumbellata, R. sylvestris, R. teres
R. alpina, R. amphibia, R. aquatica, R. austriaca, R. barbareifolia, R. calycina, R. columbiae, R. crystallina, R. curvipes, R. curvisiliqua, R. dubia, R. indica, R. microtitis, R. palustris, R. ramosa, R. sessiliflora, R. sphaerocarpa, R. subumbellata, R. sylvestris, R. tenerrima, R. teres
Synonyms Radicula tenerrima Nasturtium sinuatum, Nasturtium trachycarpum, Radicula sinuata, Radicula trachycarpa, R. trachycarpa
Name authority Greene: Erythea 3: 46. (1895) (Nuttall) Hitchcock: Key Spring Fl. Manhattan, 18. (1894)
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