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Rorippa palustris subsp. palustris
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

From Flora of Indiana (1940) by Charles C. Deam
Infrequent to frequent or even common in all parts of the state. It seems to have no preference for sun or shade and grows in wet places along streams, about ponds, lakes, and sloughs, and in ditches and fallow fields.