340 MISC. PUBLICATION 42 3, U. S. DEPT. OF AGRICULTURE 



22. Pods not strongly reflexed but sometimes recur ved-spreading 



(24). 



24. Beak of the pods stout, indehiscent, extending much beyond 



the valves; leaf blades (at least the lower ones) commonly 



lyrate-pinnatifid (25). 



25. Pods moderately compressed, the beak not tapering, 2 to 



3 mm. long; seeds in 2 rows 15 Diplotaxis. 



25. Pods terete or only slightly compressed, with a distinctly 



tapering (conic or subulate) beak usually more than 3 



mm. long; seeds in one row 16. Brassica. 



24. Beak of the pods none, or slender, or not more than 3 mm. 



long (occasionally longer in Erysimum, Conringia, and 



Cardamine) ; pods dehiscent (26) . 



26. Petals deeply lobed 18. Dryopetalon. 



26. Petals entire or inconspicuously dentate (27). 



27. Pubescence partly of forked or stellate hairs (28). 



28. Leaves pinnate, bipinnate, or very deeply pinnatifid; 

 pubescence often partly glandular. 



31. Descurainia. 



28. Leaves entire to moderately pinnatifid; glandular hairs 



none (29). 



29. Pubescence closely appressed, harsh; petals 6 mm. 



long or longer, yellow, orange, or maroon; 



stigma large, deeply 2-lobed; pods tetragonal, 



rigid 33. Erysimum. 



29. Pubescence not closely appressed; petals 6 mm. 

 long or shorter, white, whitish, or pink; stigma 

 small, entire or nearly so (30). 

 30. Stems virgate, simple or strictly few-branched; 

 leaf blades entire to coarsely dentate. 



4. Pennellia. 



30. Stems not virgate, more or less branched above, 



the branches ascending or spreading (31). 



31. Herbage finely and softly pubescent; stems lax; 



petals white; pods not more than 2 cm. long, 



not rigid, terete, with a relatively long, very 



slender beak 13. Halimolobus. 



31. Herbage coarsely and harshly pubescent; stems 

 somewhat ligid; petals purplish pink; pods 

 4 to 6 cm. long, rigid, tetragonal, very short 



beaked 34. Malcolmia. 



27. Pubescence of simple hairs or none (32). 



32. Cauline leaves pinnately cleft to pinnate (33). 



33. Pods rounded-tetragonal, elongate. 17. Barbarea. 

 33. Pods terete (34). 



34. Pods 3 cm. long or longer, about 1 mm. wide; 

 weeds of fields and roadsides, or plants of dry 



land 12. Sisymbrium. 



34. Pods not more than 2 cm. long, often more than 

 1 mm. wide; aquatic or marsh plants. 



19. Rorippa 

 32. Cauline leaves entire or merely dentate; pods elongate 

 (35). 

 35. Petals yellow; plants glabrous (36). 



36. Plant perennial; stem leaves narrow, not clasping; 

 petals somewhat channeled or crisped; pods 

 terete or nearly so; anthers deeply sagittate. 



12. Sisymbrium. 



36. Plant annual; stem leaves broad, clasping; petals 



flat; pods sharply tetragonal; anthers not or 



scarcely sagittate 35. Conringia. 



35. Petals white, pink, or purple; plants mostly peren- 

 nial (37). 



37. Stem leaves conspicuously petiolate, the blades 



deeply cordate; plant glabrous or soft-pilose; 

 anthers not sagittate 20. Cardamine. 



