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. 



Leavas stellate or with branched hairs. 

 Pod ovate or ellii)tic, compressed. 



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

 midrib of the leaves indistinct. 

 Leaves densely and closely stellate, thick. 



21. D. rentrosa. 

 Leaves sparingly long-hairy or glabrate above. 



22. D. sobolifera. 

 Pods sparingly puberulent or glabrous, not more than 3 mm. 



wide, 3-5 mm. long. 

 Leaves oblong to Unear; 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. sphaerula. 

 Pod glabrous; midvein of the leaves prominent. 



28. D. pectinata. 

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



29. D. Nelsonii. 

 Petals wliite. 



Leaves finely stellate. 



Leaves linear or linear-oblanceolate. 



Midrib of the leaves strong; pods 4-5 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-cilia'te on the margins, oblanceolate. 



Style obsolete. 33. D. fladnizensis. 



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



Plant leafy -stemmed. 



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. 



Pcts-ls vdlow 



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

 ate. 

 Leaves linear or narrowly linear-oblanceolate, tlun. 



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. slreptocarpa. 

 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 grajish; 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. 



PetaJs pale yellow; stem-leaves often dentate. 



45. D. luteola. 



