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Northern Prairie Wildlife Research Center

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Aquatic and Wetland Vascular Plants of the Northern Great Plains

22. Brassicaceae, the Mustard Family

4. Rorippa Scop. -- Yellow cress

8. Rorippa truncata (Jeps.) Stuckey

Quite similar in habit to the preceding, but sometimes taller, to 4 dm tall, the stems 1-3(5) dm long, freely branched. Leaves short-petioled or the upper ones sessile, slightly auriculate to nonauriculate, nonclasping, the blades oblong to narrowly oblanceolate, 5-12(26) cm long, 0.8-1.6(2.5) cm wide, glabrous on both surfaces or sparingly hirsute on the midrib above, mostly pinnately divided to the midrib or nearly so, the lobes entire to toothed, the terminal lobe as wide or wider than the lateral ones, mostly obtuse at the tip. Racemes lateral, without a true terminal raceme, the oldest siliques on the lower axillary racemes. Sepals green, 0.8-1.5 mm long, caducous; petals yellow, fading to whitish when dried, 0.7-1.2 mm long, shorter than the sepals. Siliques short-cylindrical, straight, constricted near the middle, not at all or only slightly tapered to the style, obtuse to truncate at the apex, 2.5-8 mm long, 1-2 mm wide, smooth or roughened with minute hyaline ridges; pedicels ascending to divergent, 1-4 mm long, glabrous. Jul--Sep. Muddy shores, flats and stream banks; uncommon and scattered; (ND to WA, s to IL, MO, TX, NM, AZ and CA). R. obtusa (Nutt.) Britt., in part.
GIF- Distribution Map

Map key

Previous Species -- Rorippa tenerrima Greene
Return to Family -- Brassicaceae - The Mustard Family
Next Species -- Thelypodium integrifolium (Nutt.) Endl.

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