286 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



Siliqucs beaked; .seeds glol)ose 14. Bras.sica (p. 301). 



Siliques beakless; seeds oblong. 



Valves of the pods nerveless 9. Roripa (p. 296). 



Valves of the pods nerved. 



Annuals; leaves pinnate or 



pinnatifid 15. Sisymbrium (p. 301 ) . 



Perennials. 



Leaves entire or suben- 



tire 16. Sciioenocrambe ( p. 303 ) . 



Leaves lyrate 17. Campe (p. 303). 



Pods short, therefore silicles. 



Silicles conipre.ssed parallel to the partition. 



Flowers solitary on scapes, white ; seeds winged . 1 . Platyspermum ( p. 286) . 

 Flowers racemose; seeds wingless. 



Silicles orbicular 2. Alyssum ( p. 287) . 



Silicles ovate or oblong 3. Draba (p. 287) . 



Silicles not compressed, or compressed contrary to 

 the partition. 



Plant aquatic, submerged; leaves subulate; pods 



subglobose 18. Subularia (p. 303) . 



Plants terrestrial; leaves not subulate. 

 Pods terete, not compressed. 



Pubescence stellate ; pods globose 10. Lesquerella (p. 298). 



Pubescence not stellate; pods oblong. 9. Roripa (p. 296). 

 Pods compressed contrary to the partition. 



Valves nerveless; pod obcordate. .... 24. Physaria (p. 306). 

 Valves 1-nerved. 



Nerves of the valves obtuse, not 

 prominent. 



Silicles cuneate, notched at 



apex 19. Bursa (p. 303) . 



Silicles not cuneate; not 

 notched at apex. 



Cauline leaves sessile; 



pod elliptic 20. IIutchinsia (p. 304). 



Cauline leaves auricu- 



late; pod obovoid ... 21. Camelina (p. 304). 

 Nerves of the valves forming 

 acute keels or wings. 



Silicles orbicular or obovate; 



cells 1 or 2-seeded 22. Lepidium (p. 304). 



Silicles ovate or oblong; sili- 

 cles 2 to several seeded 23. Tiilaspi (p. 305). 



PLATYSPERMUM. 



1. Platyspermum. scapigerum Hook. Fl. Bor. Am. 1: 68. 1830. 



Type i.ocamty: "Moist rocks and in shallow soil at the Great Falls [Celilo Falls] of the 

 Columbia." Collected by Douglas. 



Range: Washington and Idaho to Nevada. 



Specimens examined: Klickitat Valley, Howell; Colville, Lyall, March 31, 1861; Pull- 

 man, Elmer 82; Pi-per, April, 1894, May, 1893. 



Zonal distribution: Arid Transition. 



The stamens in this plant are variable in number, not unconunonly 4 or 5 in place of 

 the normal 6. The peppery pods are eaten by children. 



