MUSTARD FAMILY 351 



Plant densely pulvinate; leaves linear-oblong, villous-hispid as 



well as stellate, densely imbricate. 20. D. densifolia 



Pods only slightly longer than broad. 



Leaves stellate or with branched hairs. 

 Pod ovate or elliptic, compressed. 



Pods densely stellate, about 5 mm. long, fully 4 mm. wide; 



midrib of the leaves indistinct. 

 Leaves densely and closely stellate, thick. 



21. D. ventrosa. 

 Leaves sparingly long-hairy or glabrate above. 



Pods sparingly puberulent or glabrous, not more than* slnm 



wide, 3-5 mm. long. 

 Leaves oblong to linear; midvein strong. 



Plants not densely pulvinate; leaves linear or linear-ob- 



lanceolate, 5-10 mm. long. 23. D. oligosperma 



Plant densely pulvinate; leaves oblong or linear-oblong 

 less than 5 mm. long, densely imbricate. 



24. D. andina 

 Leaves obovate, thick; midvein indistinct. 



25. D. uncinalis. 

 Pod globose. 26. D. sphaerocarpa. 



Leaves glabrous except the unbranched ciliations on the margins. 

 Leaves densely imbricate, short. 



Pod pubescent ; midvein of the leaves obsolete. 



27. D. sphacrula 

 Pod glabrous ; midvein of the leaves prominent. 



28. D. pectinata. 

 Leaves not densely imbricate; pod pubescent, 3-6 mm. long 



29. D. Nelsonii. 

 Petals white. 



Leaves finely stellate. 



Leaves linear or linear-oblanceolate. 



Midrib of the leaves strong; pods 45 mm. long. 



23. D. oligosperma. 

 Midribs of the leaves not strong; pods 6-8 mm. long. 



30. D. lapponica. 

 Leaves broadly spatulate or obovate. 



Pod oblong to linear, 6-12 mm. long. 



Pods 6-8 mm. long, not twisted. 31. D. nivalis. 



Pods 10-15 mm. long, more or less twisted. 32. D. lonchocarpa. 

 Pods broadly obovate, 3-4 mm. long. 25. D. uncinalis 



Leaves hirsute-ciliate on the margins, oblanceolate. 



Style obsolete. 33. D. flarfnizensis. 



Style about 1 mm. long. 34. D. oreibata. 



Plant leafy -stemmed. 

 Petals white. 



Petals about 3 mm. long; pods 5-8 mm. long. 



Plant 1-2 dm. high, densely grayish-stellate; pods longer than the pedicels. 



35. D. cana. 

 Plants about 3 dm. high, greener; pods shorter than the pedicels. 



36. D. McCallae. 

 Petals about 2 mm. long; pods more than 1 cm. long. 37. D. columbiana. 



Petals yellow. 



Plants glabrous, except the margins of the leaves, which are occasionally cili- 



ate. 

 Leaves linear or narrowly linear-oblanceolate, thin. 



Leaves much shorter than the flowering stem; pods lance-linear. 



38. D. chrysantha. 

 Leaves almost equalling the flowering stem; pods ovate. 



39. D. graminea. 

 Leaves spatulate or broadly oblanceolate, thick. 40. D. crassa 



Plant decidedly hairy. 



Pubescence long-hirsute, with simple or slightly branched hairs. 



41. D. streptocarpa. 

 Pubescence short, mostly of stellate or branched hairs. 



Styles 1.5-2 mm. long; pods glabrous or slightly puberulent. 



Pod not twisted; pubescence rather sparse or minute; stem-leaves 



usually sharply toothed. 



Stem more or less hirsute. 42. D. spectabilis. 



Stem minutely appressed-stellate. 43. D. oxyloba. 



Pod twisted; pubescence dense and grayish; stem-leaves entire- 

 margined or minutely denticulate. 44. D. Helleriana. 

 Style 1 mm. long; pods densely pubescent. 

 Stem erect or nearly so. 



Leaves thin, the basal ones usually over 2 cm. long, the cauline 



ovate to lanceolate. 

 Petals 5 mm. or more long. 



Petals pale yellow; stem-leaves often dentate. 



45. D. luteola. 



