Rorippa palustris (L.) Besser

Herb

Rorippa species are aquatic or mesic, annual, biennial or perennial herbs, glabrous or pubescent with simple trichomes, not scapose. Rootstocks rhizomatous, caudex sometimes present. Stem erect or prostrate, ascending, leafy, simple or branched. Basal leaves simple, rosulate or not, usually withered before flowering, obovate-oblanceolate to oblong, base cuneate to attentuate, margin entire, sinuate dentate, lyrate to pinnatisect, apex acute, petiolate, cauline leaves usually gradually smaller, base cuneate, margin entire, dentate to pinnatisect, petiole short to sessile. Inflorescence racemes, many flowered, considerably elongated in fruit, ebracteate, rarely bracteate. Flowers bisexual, yellow, white or pink, pedicel erect or slightly curved, divaricate or reflexed, slender, ascending, sepals 4, erect or spreading, linear ovate-oblong, margin membranous, inner lateral pair base rarely saccate, petals 4 or rarely absent, obovate-oblanceolate to spathulate, margins entire, apex obtuse or emarginate, claw distinct, usually shorter than sepals. Stamens 6 rarely 4, tetradynamous, filaments not dilated near the base, anthers ovate-oblong, apex obtuse rarely apiculate, nectar glands 4 confluent, usually subtending the bases of stamens, median glands present. Ovary superior, bicarpellary, ovules 10-250. Fruit siliqua or silicles, dehiscent, linear cylindrical, ellipsoid or obovoid, sessile or shortly stipitate, terete, erect or slightly curved, latiseptate, smooth or torulose, valves chartaceous with prominent or obscurely veined, replum rounded, septum complete, style obsolete or short, stigma capitate, entire or slightly bilobed. Seeds usually biseriate, rarely uniseriate, brown, plump, elliposid, oblong-ovoid, not winged or rarely winged, minutely reticulate, mucilaginous or not when soaked, cotyledons accumbent.

Rorippa species flowers are complete, bisexual, i.e., with functional male (androecium) and female (gynoecium), including stamens, carpels and ovary. Pollination is entomophilous i.e., by insects, or cleistogamy i.e., by self or allogamy i.e., by cross pollination. Flowering/Fruiting: April—July.

Seeds may be dispersed by autochory i.e., self dispersal, anemochory i.e., wind dispersal, zoochory i.e., dispersal by birds or animals, anthropochory i.e., dispersal by humans.

Annual, biennial or rarely short lived perennial herbs, usually glabrous or rarely sparsely pubescent with simple cylindrical trichomes, about 10-100 cm tall, not scapose. Stem erect or ascending, leafy, simple or branched from slightly above. Basal leaves in rosulate or not, usually withered before flowering, obovate-oblanceolate in outline, about 5-20 x 1-4.5 cm across, margin lyrately pinnatisect, lateral lobes 2-6 if present, gradually becoming larger towards the apex, terminal lobe the largest, lobe margin crenate, apex obtuse, petiole up to 1-4 cm long, cauline leaves gradually smaller, base auriculate or amplexicaul, margin irregularly serrate dentate, crenate or rarely entire, apex subacute to obtuse, glabrous both above and beneath, sometimes sparsely pubescent beneath, petiole subsessile to sessile. Inflorescence raceme corymbs, many flowered, about 10-30 cm long, elongated in fruit, ebracteate. Flowers bisexual, yellow, pedicel erect or reflexed, divaricate, slender, ascending, about 3-10 mm long, sepals 4, erect, linear oblong, margin membranous, inner lateral pair base rarely saccate, about 2-3 x 0.5-1 mm across, petals 4, obovate-spathulate, margins entire, apex emarginate, about 1.8-2.5 x 0.6-1.5 mm across. Stamens 6, tetradynamous, filaments not dilated near the base, about 1.5-2 mm long, anthers oblong, about 0.3-0.5mm long, apex obtuse rarely apiculate. Ovary superior, bicarpellary, ovules 20-90. Fruit siliqua, dehiscent, ellipsoid, about 5-12 x 2-2.5 mm across, sessile, erect or slightly curved, latiseptate, smooth or torulose, valves chartaceous with prominent midvein, replum rounded, septum complete, style about 0.3-0.9 mm long, stigma capitate, entire or slightly bilobed. Seeds biseriate, reddish brown, slightly compressed, orbicular, ovate-ovoid, about 0.5-0.8 mm long, minutely reticulate, colliculate, mucilaginous or not when soaked, cotyledons accumbent.

Rorippa species are susceptible to various insect pests, virus, mildews and moulds.

Moist places

Humid marshy places, near streams and lakes, altitude 2000-3300 m.

Not evaluated (IUCN).

Leaves are edible, also used as antiscorbutic.