The
photo at right shows two forms of stem leaves found on marsh yellowcress.
Also known as marsh cress, marsh yellowcress is an erect, freely branched biennial with glabrous to sparsely haired stems from 30-100 cm high. The leaves are ovate-oblong to oblong obovate in outline and range from coarsely toothed near the tip to pinnatifid or lobed. The lobed segments are often further toothed. The basal and lower stem leaves measure up to 17 cm long while those of the upper stem become reduced in size. Some of the leaves are broadly petiolate while others taper gradually to wide bases that have heart-shaped, clasping bases on the stem.
The numerous racemes are at the tips of the upper branches. The pedicels are 4-12 mm long while the 4 sepals are 1.5 mm long with pouched bases. The 4-petalled flowers have light yellow petals from 1-2 mm long. The fruits are spreading to ascending siliques which are ovate to oblong in shape, the axis straight to slightly arched. The siliques, which are shorter than to nearly equal in length as the pedicels, are 3-8 mm long and 2-3 mm wide.
Marsh yellowcress is found in wet places in marshes, swamps, streambanks and ditches.
Marsh yellowcress may be found over much of the Northern Hemisphere. In North America, it may be found from Canada south to near the Mexican border.
