Northern Prairie Wildlife Research Center
Aquatic and Wetland Vascular Plants of the Northern Great Plains
22. Brassicaceae, the Mustard Family
4. Rorippa Scop. -- Yellow cress
7. Rorippa tenerrima Greene
Glabrous, decumbent to prostrate annual, much-branched from the base, the stems
1-2 dm long. Leaves short-petioled, nonauriculate and nonclasping, the
blades oblong or oblanceolate to spatulate, 2-5(8) cm long, 0.8-1.5 cm wide,
lyrate-divided nearly to the midrib, rarely undivided, the lobes entire, the
terminal lobe wider than the lateral ones, obtuse at the tip. Racemes
terminal and axillary or all lateral, all about the same age or the lowest racemes
with the oldest siliques. Sepals green, 0.7-1.2 mm long, caducous; petals
yellow, fading to whitish when dried, 0.6-0.8 mm long, shorter than the sepals.
Siliques elongate-cylindrical, slightly curved, tapering to the style,
not constricted at the middle, 3-8 mm long, 0.8-2 mm wide, roughened with minute
papillae; pedicels ascending, 1.5-4 mm long, usually rough with papillae.
Jul--Sep. River bottoms and stream banks; rare, with collections from along
the Missouri R., c ND, also sw SD and w NE; (MT to WA, s to NM and CA, sparingly
e along major rivers to ND, SD, NE and MO). R. obtusa (Nutt.) Britt.,
Previous Species -- Rorippa sylvestris (L.) Bess.
-- Creeping yellow cress
Return to Family -- Brassicaceae -
The Mustard Family
Next Species -- Rorippa truncata (Jeps.) Stuckey