62 CRUCIFERiE. Draba. 



2. SILICULOSiE. 

 Tribe IV. ALYSSINE^. 



Silicle dehiscent ; valves plane or convex ; septum broadly oval and membranaceous. Seeds 

 compressed, often margined. Cotyledons plane, accumbent, ■parallel to the septum. 



10. DRABA. Linn.; Endl. gen. 4:880. wbitlow-grass. 



[Named from the Greek, draie, acrid; from taste of the leaves in many of the genus.] 



Silicle oval or oblong ; valves plane or convex. Seeds numerous, not margined. Calyx equal. 

 Petals entire or bifid. Stamens all toothless. — Herbs of various habit. Flowers white or 

 yellow. 



§ 1. Draba, DC. Petals entire. 



1. Draba arabisans, Michx. Arabis-like Whitlow-grass. 



Perennial : whole plant slightly and stellately pubescent ; stem leafy, simple, or branching 

 from the base ; leaves sparingly and acutely toothed ; radical ones cuneiform-lanceolate, the 

 cauline oblong ; silicles smooth, lanceolate-oblong, contorted, pointed with a very short but 

 distinct style; petals (white) about twice as long as the sepals. — Michx. jl. 2. p. 28; DC. 

 prodr. 1. p. 70 ; Hook. Jl. Bor.-Am. p. 55 ; Torr. ^ Gr.jl. N. Am. 1. p. 106. D. incana, 

 /S. glabriuscula, Gray in ann. lye. N. York, 3. p. 223. 



Stems usually several from one root, 6-12 inches high. Radical leaves numerous, form- 

 ing a circular tuft, about an inch long, acute, with a long tapering base, 1 - 2-toothed or entire ; 

 cauline ones slightly clasping, furnished with one or two (rarely more) very acute spreading 

 teeth on each side. Flowers about three lines in diameter. Petals broadly ovate. Raceme 

 of fruit 4-6 inches long. Silicle half an inch long, and nearly 2 lines wide, nearly erect. 

 Pedicels about half as long as the silicles, often cohering at the base by pairs. Seeds 

 7 - 10 in each cell. 



Rocky borders of lakes and rivers in the northern part of the State. Fl. May - June. 

 Fr. July. 



2. Draba Caroliniana, Walt. CaroUiia Whitlow-grass. 



Annual. Stem leafy and hispid at the base, naked and smooth above, leaves ovate ; entire, 

 hispid ; silicles linear, smooth, somewhat corymbed, longer than their pedicels ; style almost 

 none ; (flowers while.)— Walt. Jl. Car. p. 174 ; Ell. sk. 2. p. 138 ; DC. prodr. 1. p. 171 ; 

 Torr. ^ Gr. Jl. N. Am. 1. p. 109. D. hispidula, Michx. Jl. 2. p. 28 ; Pursh, Jl. 2. p. 433. 

 Arabis rotundifolia, Raf. in Amer. month, mag. 2. p. 43. 



Plant 2-5 inches high ; the pubescence branched. Stems commonly several from one 

 root, branching from near the base ; the branches widely spreading. Leaves 4-5 lines long, 

 the radical and lower cauline ones abruptly narrowed at the base. Flowers nearly twice as 



