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Rorippa palustris subsp. palustris (L.) Besser
Family: Brassicaceae
bog yellowcress
Rorippa palustris subsp. palustris image
Stems usually glabrous, rarely sparsely pubescent proximally. Leaf blades: abaxial surface usually glabrous, rarely sparsely pubescent proximally. 2n = 32. Flowering Mar-Sep. Marshlands, pastures, prairies, meadows, swales, flats, sand bars, wet grounds, stream banks, moist depressions, ditches, estuaries, waste grounds, roadsides, sloughs, shores of lakes and ponds, bogs, thickets, grasslands; 0-3200[-4000] m; Alta., B.C., Man., Nfld. and Labr., N.W.T., N.S., Ont., P.E.I., Que., Sask., Yukon; Ala., Alaska, Ariz., Ark., Calif., Colo., Conn., Del., D.C., Fla., Ga., Idaho, Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Mont., Nebr., Nev., N.H., N.J., N.Mex., N.Y., N.C., N.Dak., Ohio, Okla., Oreg., Pa., R.I., S.C., S.Dak., Tenn., Tex., Utah, Vt., Va., Wash., W.Va., Wis., Wyo.; Europe; Asia; introduced in n Mexico, South America, Australia.
Annual or biennial herb with a taproot mostly 10 cm - 1 m tall Stem: upright, branched, mostly under 3 mm thick, sometimes sparsely hairy below. Leaves: alternate, often pinnately divided (especially lower leaves), lance-shaped to oblong- reverse egg-shaped, thin. The middle stem leaves are generally winged toward the lobed base, looking more or less stalkless. Flowers: in loose, branched clusters (racemes). Sepals four, ascending. Petals four, yellow, 1.5 - 2.5 mm long, about as long as sepals, bases narrowed. Stamens six. Fruit: a longish, plump pod (silique), 4 - 9 mm long, twice as long as stalks, more or less round in cross-section, not constricted in the middle.

Similar species: No information at this time.

Flowering: July to September

Habitat and ecology: Typically found in mud, sand flats, and other moist areas.

Occurence in the Chicago region: native

Etymology: Rorippa possibly comes from the Latin roro, meaning "to be moist," and ripa, meaning riverbank. Palustris means "marsh-loving."

Author: The Morton Arboretum