annual, biennial, or perennial herbs, terrestrial or aquatic, glabrous or
pubescent with unbranched hairs. Stems erect to spreading, unbranched or
branched. Leaves alternate and sometimes also basal, short-petiolate or
sessile, not clasping the stem or the petiole base with small, rounded
auricles. Leaf blades simple or pinnately divided or compound. Inflorescences
racemes or panicles with the lower branches sometimes subtended by reduced,
leaflike bracts, the flowers bractless (with bracts elsewhere). Sepals ovate to
narrowly oblong, erect or ascending, often green or yellowish. Petals not
lobed, yellow (white in R. aquatica), sometimes absent. Stamens (4)6.
Styles absent or 0.5–4.0 mm long. Fruits spreading or ascending, 1 or
more times as long as wide, ovate to oblong or linear (circular elsewhere) in
outline, circular in cross-section or nearly so or somewhat flattened at a
right angle to the septum, straight or curved upward, the valves not veined or
with a single, indistinct midnerve, dehiscent longitudinally. Ovules mostly in
2 rows in each locule. Seeds 5–100(–300) per locule. Seventy-five
to 80 species, nearly worldwide.
species of Rorippa have been collected for use as a salad green or
vegetable. While in Missouri in 1803 during the early days of their epic
voyage, the Lewis and Clark Expedition collected some species of Rorippa
along the Missouri River both for food and as a pressed specimen (Meehan, 1898;
see also the introductory chapter on the history of floristic botany in
Missouri in the first volume of the present work [Yatskievych, 1999]).