ISO 



CRUCIFERAE. 



Vol. it. 



5. Draba nivalis T.ilj. Yellow Arctic 

 Whitlow-grass. Fig. 2001. 



Draba nivalis Lilj. Vel. AUad. Handl. 1793 : 208. 1793. 



Perennial by a short branched caudex ; scapes 

 tufted, somewhat pubescent, slender, leafless or 

 sometimes bearing a small sessile leaf, i'-4' 

 high. Basal leaves usually numerous, tufted, 

 oblanccolate or spatulate, 2"-7" long, entire, 

 acutish or acute at the apex, narrowed into a 

 short petiole, stellate-canescent, not eiliate, or 

 slightly so near the base ; flowers yellow, about 

 2" broad; calyx pubescent; style short; pods 

 oblong or linear-oblong, narrowed at both ends, 

 glabrous or but little pubescent, on ascending 

 pedicels i"-3" long. 



Labrador and Greenland, through arctic America 

 to Alaska, south in the Rocky Mountains to Colorado, 

 and in the Sierra Nevada to Nevada. Also in north- 

 ern Europe and Asia. Summer. 



6. Draba incana I.. Hoary or Twisted 

 Whitlow-grass. Fig. 2002. 



Draba incana L. Sp. PI. 643. 1753. 

 Draba confusa Ehrh. Beitr. 7: 155. i79-- 



Perennial or biennial ; flowering stems erect, sim- 

 ple or somewhat branched, leafy, loosely pilose- 

 pubescent, 16' high or less. Leaves 4"-i2" long, 

 acutish or obtuse, dentate or nearly entire, the basal 

 ones oblanceolate, those of the flowering stems 

 lanceolate to ovate ; flowers white, i"-ii" broad ; 

 petals notched, twice as long as the calyx ; pods 

 oblong or lanceolate, acute, twisted when ripe, on 

 short nearly erect pedicels, densely pubescent or gla- 

 brous ; style minute. 



In rocky places, Newfoundland and Labrador to Que- 

 bec. Also in arctic and alpine Europe. Hunger-flower. 

 Nailwort. Summer. 



Draba hirta L, of high boreal regions has fewer stem- 

 leaves and longer fruiting pedicels. 



7. Draba arabisans Michx. Rock-cress 

 Whitlow-grass. Fig. 2003. 



D. arabisans Michx. FI. Bor. Am. 2: 28. 1803. 

 D. incana arabisans S. Wats. Proc. Am. Acad. 23: 



260. 1888. 

 D. arabisans orthocarpa Fernald, Rhodora 7 ; 66. 



1905. 



Perennial by a slender branched caudex, the 

 flowering stems 6'-2o' high, sparingly stellate- 

 pubescent, often numerous. Leaves thin, green, 

 loosely and mostly sparingly stellate-pubescent, 

 the tufted basal ones spatulate to oblanceolate, 

 i'-2V long, 2"-4" wide, usually remotely den- 

 tate, sometimes entire, those of the flowering 

 stems similar, oblong to spatulate ; flowers 

 white ; fruiting pedicels slender, divergent- 

 ascending, 5" long or less; pods narrowly ob- 

 long, glabrous, z"-?" long, l"-2" wide, twisted 

 or straight. 



On cliffs and in rocky and sandy soil, New- 

 foundland and Labrador to Maine, Vermont, 

 northern New York and western Ontario. June- 

 Aug. 



