Rorippa austriaca

Perennials; (terrestrial or of wet habitat, not submerged, rhizomes thickened, short); usually gla-brous, rarely pubescent proximally. Stems (simple from base), erect, much-branched distally, 4-11(-18) dm. Basal leaves not rosulate; blade margins pinnatifid. Cauline leaves sessile; blade lanceolate, (2.5-)4-12(-15) cm × 5-20(-25) mm, base auriculate to amplexicaul, margins entire or serrate. Racemes elongated. Fruiting pedicels divaricate-ascending to horizontal, straight, 4-15 mm. Flowers: sepals ascending, oblong, 2-3 × 1-1.3 mm; petals yellow, obovate, 3-5 × 1.7-2.5 mm; median filaments 2.3-3 mm; anthers ovate, 0.4-0.6 mm. Fruits silicles (rarely produced), straight, globose or subglobose, 2.5-3.2 × 1.5-2.7 mm; ovules 18-40 per ovary; style 1-1.5(-2) mm. Seeds biseriate, reddish brown, ovoid, 0.7-0.9 mm, finely colliculate. 2n = 16.

Flowering May-Jul. Mud flats, floodplains, fields, roadsides, lakeshores, marshes, ditches, stream banks, wet grasslands, waste grounds; 100-1900 m; introduced; Alta., Man., Sask.; Calif., Conn., Idaho, Ill., Iowa, Nebr., Nev., N.J., N.Mex., N.Y., N.Dak., Pa., Utah, Wash., Wis.; Europe.

Perennial herb to 60 cm tall Leaves: alternate, stalked, not clasping, 3 - 10 cm long, reverse lance-shaped, bases lobed, tips rounded, slightly toothed to toothed. Flowers: in branched clusters (racemes). Sepals ascending. Petals four, yellow, slightly longer than sepals, bases narrowed. Stamens six. Fruit: a short pod, long-stalked, 1 - 2 mm long, about as long as wide, shorter than stalks, rounded. Seeds often not maturing. Roots: creeping, thick, fleshy.

Similar species: No information at this time.

Habitat and ecology: Introduced from Europe. In the Chicago Region, this field weed is known only from Walworth County, Wisconsin, where it was collected in 1968 from a large roadside colony.

Occurence in the Chicago region: non-native

Etymology: Rorippa possibly comes from the Latin roro, meaning "to be moist," and ripa, meaning riverbank. Austriaca means Austrian.

Author: The Morton Arboretum

Perennial to 6 dm, from rather thick and fleshy creeping roots; lvs oblanceolate, 3-10 cm, mostly obtuse, dentate to subentire, gradually tapering to an auriculate base; pet slightly longer than the sep; mature pedicels ascending, 7-15 mm; frs globose, 1-2 mm, about as long as wide, the replum circular in outline, often not maturing seeds; style about as long as the fr; 2n=16. Native of Europe, sparingly established as a weed in fields here and there in our range. June, July.

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

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