14. Rorippa palustris (Linnaeus) Besser, Enum. Pl. 27. 1821. (as Roripa).
Sisymbrium amphibium Linnaeus var. palustre Linnaeus, Sp. Pl. 2: 657. 1753; Brachiolobos palustris (Linnaeus) Clairville; Cardamine palustris (Linnaeus) Kuntze; Caroli-Gmelina palustris (Linnaeus) P. Gaertner, B. Meyer & Scherbius; Myagrum palustre (Linnaeus) Lamarck; Nasturtium palustre (Linnaeus) de Candolle; Radicula palustris (Linnaeus) Moench
Annuals or, rarely, perennials; (short-lived, terrestrial or of wet habitat, not submerged); usually glabrous, rarely hirsute, (trichomes cylindrical). Stems (often simple from base), erect, branched distally, (0.5-)1-10 (-14) dm, (sometimes hirsute proximally). Basal leaves rosulate; blade [(4-)6-20(-30) cm × 10-50(-80) mm] margins lyrate-pinnatisect, (abaxial surface sometimes hirsute). Cauline leaves petiolate or subsessile; blade lyrate-pinnatisect, (lateral lobes oblong or ovate when present), (1.5-)2.5-10(-18) cm × (5-)8-25(-30) mm, (lateral lobes smaller than terminal), base auriculate or amplexicaul, margins subentire or irregularly dentate, sinuate, serrate, or crenate, (abaxial surface sometimes hirsute). Racemes often considerably elongated. Fruiting pedicels divaricate or slightly to strongly reflexed, straight or curved, (2.5-)3-10(-14) mm. Flowers: sepals erect, oblong, 1.5-2.4(-2.6) × 0.5-1 mm; petals yellow or pale yellow, spatulate, (1.5-)1.8-2.5(-3) × 0.5-1.5(-2) mm; median filaments 1-2.5 mm; anthers ovate, 0.3-0.5 mm. Fruits usually silicles, rarely siliques, often slightly curved, oblong, ellipsoid, or oblong-ovoid, (2.5-)4-10 × (1.5-)1.7-3(-3.5) mm; ovules 20-90 per ovary; style 0.2-1(-1.2) mm. Seeds biseriate, brown to yellowish brown, ovoid or subglobose, 0.5-0.7(-0.9) mm (0.4- 0.6(-0.7) mm diam.), colliculate.
Subspecies 2 (2 in the flora): North America, Europe, Asia; introduced in n Mexico, South America, Australia.
