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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

2. Rorippa calycina (Engelm.) Rydb.

Decumbent to prostrate, much-branched perennial from rhizomes, 1-4 dm tall, moderately to densely hirsute with slender, elongate trichomes. Leaves sessile, the blades oblong to oblanceolate in outline, 2.5-5 cm long, 0.5-1 cm wide, hirsute on both surfaces, especially on the midrib, acute to obtuse, shallowly to deeply sinuate, auriculate and partly clasping at the base. Racemes terminal and axillary, all about the same age or the lowest ones with the oldest siliques. Sepals yellowish-green, 2.1-3.1 mm long, persistent with fruit; petals bright yellow, (2)2.5-3.7 mm long, to 1 mm longer than the sepals. Siliques globose to subglobose, 2.3-3.4 mm long, 1.2-2.3 mm wide, ca. 1.3-2X longer than wide, densely strigose on the valves; pedicels strongly recurved, sometimes giving the raceme a 1-sided appearance, 3.5-6.5 mm long. May--Jul. Rare or possibly extinct in this region, with old collections from w ND, MT, WY and w NE; (N.W.Terr., w ND, MT, WY and w NE).
GIF- Distribution Map

Map key

Previous Species -- Rorippa austriaca (Crantz) Bess. -- Austrian field cress
Return to Family -- Brassicaceae - The Mustard Family
Next Species -- Rorippa curvipes Greene

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