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