278 BRASSICACEAE 



slender, 6 mm. long ; pods linear-oblong, straight or slightly curved, smooth or slightly rough- 

 ened, 8-14 mm. long ; style slender, 2-3 mm. long. 



Moist sandy soil, mainly Upper Sonoran Zone; eastern Washington and Oregon to Saskatchewan, Illinois, 

 Texas, and Arizona. Type locality: "Banks of the Oregon [Columbia] and its tributaries." April-Sept. 



3. Rorippa columbiae Suksdorf. Columbia Yellow-cress. Fig. 2024. 



Nasturtium sinuatum var. columbiae Suksdorf ex Robinson, Syn. Fl. N. Amer. I 1 : 147. 1895. 

 Rorippa columbiae Suksdorf ex Howell, Fl. N.W. Amer. 1: 40. 1897. 

 Nasturtium columbiae Suksdorf, Deutsch. Bot. Monatss. 16: 211. 1898. 

 Radicula columbiae Greene, Leaflets Bot. Obs. 1: 114. 190S. 



Plants perennial by creeping rootstocks, pubescent throughout, the stems low and spreading. 

 Leaves pinnatifid, with many oblong, often toothed segments; pedicels ascending or spreading; 

 petals 4 mm. long; pod ascending or erect, short-oblong, curved, densely puberulent or some- 

 what papillose ; style nearly 2 mm. long. 



Moist sandy soil, Transition and Upper Sonoran Zones; eastern Washington and Oregon to Montana, 

 Nebraska, and New Mexico. Type locality: "low gravelly banks of the Columbia River, near Bingen," Wash- 

 ington. May-Sept. 



4. Rorippa curvisiliqua (Hook.) Bessey. Western Yellow-cress. Fig. 2025. 



Sisymbrium curvisiliqua Hook, Fl. Bor. Amer. 1:61. 1830. 

 Nasturtium curvisiliqua Nutt. in Torr. & Gray, Fl. N. Amer. 1: 73. 1838. 

 Nasturtium lyratum Nutt. in Torr. & Gray, Fl. N. Amer. 1 : 73. 1838. 

 Rorippa curvisiliqua Bessey, Mem. Torrey Club 5: 169. 1894. 

 Radicula curvisiliqua Greene, Leaflets Bot. Obs. 1: 113. 1905. 



Annual or biennial, glabrous, the stems usually diffusely branched, the branches ascending, 

 1-3 dm. high. Leaves pinnatifid, with oblong, mostly obtuse segments ; pedicels 2-6 mm. long ; 

 pod curved, 8-12 mm. long, about 1 mm. thick ; style less than 1 mm. long. 



Wet places, Upper Sonoran and Transition Zones; British Columbia to Wyoming, and through the Pacific 

 States to Lower California. Type locality: "Common on the Northwest coast of America, Latitude 47° to 

 48°, in sandy soils, near streams." March-Nov. 



5. Rorippa obtusa (Nutt.) Britt. Blunt-leaved Yellow-cress. Fig. 2026. 



Nasturtium obtusum Nutt. in Torr. & Gray, Fl. N. Amer. 1: 74. 1838. 

 Rorippa obtusa Britt. Mem. Torrey Club 5: 169. 1894. 

 Radicula obtusa Greene, Leaflets Bot. Obs. 1: 113. 1905. 



Annual, glabrous, the stems diffusely branched at the base, 1-3 dm. high. Leaves pinnatifid, 

 with obovate or rounded, sinuately toothed divisions; pedicels ascending or spreading, 2-4 mm. 

 long; petals narrowly spatulate, 1 mm. long; pods 4-8 mm. long, 1-2 mm. thick; style about 

 1 mm. long. 



Wet places, Upper Sonoran and Arid Transition Zones; eastern Washington to southern California, east 

 to Michigan, Utah, Texas, and Missouri. Type locality: "banks of the Mississippi." May-Sept. 



6. Rorippa palustris (L.) Bess. Marsh Yellow-cress. Fig. 2027. 



Sisymbrium amphibium var. palustre L. Sp. PI. 657. 1753. 



Radicula palustris Moench, Meth. 263. 1794. 



Nasturtium terrestre R. Br. in Ait. Hort. Kew. ed. 2. 4: 110. 1812. 



Rorippa palustris Bess. Enum. PI. Volh. 27. 1821. 



Nasturtium palustre DC. Syst. 2: 191. 1821. 



Annual or biennial, glabrous or nearly so, its stems erect, branching above, 3-8 dm. high. 

 Lower leaves lyrate-pinnatifid, petiolate, the upper nearly sessile, dentate or somewhat lobed; 

 pedicels slender, 6 mm. long in fruit ; petals 2 mm. long ; pods linear or linear-oblong, spreading 

 or curved, 5-7 mm. long; style 1 mm. long. 



Marshes, often growing in water, Boreal and Austral Zones; Alaska to Labrador south to California, 

 Georgia, and Mexico; also Europe and Asia. Type locality: in Europe. May-Sept. 



Rorippa palustris subsp. occidentale (S. Wats.) Abrams. {Nasturtium terrestre var. occidental S. Wats, 

 in A. Gray, Syn. Fl. N. Amer. I 1 : 148. 1895; Rorippa pacifica Howell, Fl. N.W. Amer. 40. 1897; R. palus- 

 tris var. pacifica G. N. Jones, Univ. Wash. Pub. Biol. 5: 161. 1936.) Mainly distinguished by the longer 

 (8-12 mm.) pods. This is the more common form of the species on the Pacific Coast ranging from Alaska 

 to central California. 



7. Rorippa hispida (Desv.) Britt. Hispid Yellow-cress. Fig. 2028. 



Brachylobus hispidus Desv. Journ. Bot. 3: 183. 1814. 



Nasturtium hispidum DC. Syst. 2:201. 1821. 



Rorippa hispida Britt. Mem. Torrey Club 5: 169. 1894. 



Radicula hispida Britt. Torreya 6: 30. 1906. 



Radicula palustris var. hispida Robinson, Rhodora 10: 32. 1908. 



Annual or biennial, the stems stout, erect, branching above the base, 3-12 dm. high, the 

 branches, petioles and veins on the lower surface of the leaves hirsute with spreading hairs. 

 Leaves lyrate-pinnatifid; pedicels slender, spreading, about 6 mm. long, pods ovoid, 4-6 mm. 

 long, glabrous ; style 1 mm. long. 



Marshes, often growing in shallow water, Boreal and Austral Zones; Alaska to New Brunswick, south 

 to Washington, California, New Mexico, and Florida. Type locality: Pennsylvania. June-Aug. 



