188 Cruciferaceae 
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E. Flowers distant in the raceme; pod 2—4 mm. long. W. 
D. brachycarpa Nutt. _(Short-pod Whitlow-grass) 
EE. Flowers close in the raceme; pod 8—12 mm. long. ¥ 
F. Pod glabrous. E : 
D. earoliniana Walt. (Carolina Whitlow-grass) 
FF. Pod short-hairy. E. (D. micrantha.) 
D. caroliniana micrantha Gray 
DD. Biennial or perennial, either woody at base or else scapose and caespitose. 
G. Leaves keeled by the prominent mid-vein. 
H. Leaves linear to oblong. E. ° 
D. oligosperma Hook. 
HH. Leaves linear-spatulate to oblanceolate. E. 
D. douglasii Gray 
GG. Leaves flat, not keeled by the prominent mid-vein. C. (D. laevipes.) 
YD. lonchocarpa Rydb. 

AA. Flowers yellow. 
I. Annual; stems not woody, somewhat leafy. 
J. Leaf-blade widest at or above its middle; pedicels about equaling the pods; 
pod 8—1[5 mm, long.- -W. C.__E: 
D. stenoloba Ledeb. 
JJ. Leaf-blade widest below its middle; pedicels longer than the pods; pod 6—8 
mm. long. W. E. (D. nemorosa lutea.) 
D. nemorosa L. . (Wood Whitlow-grass) 
II. Perennial; stem either woody at base or else scapose from caespitose plants. 
K. Leaves flat, not keeled; plants with branching leafy-tufted caudex. 
L. Stems scapose above the caudex. 
M. Leaf-blade widest above its middle. (See N.) 
MM. Leaf-blade widest at or below its middle. 
N. Petals 6—8 mm. long; pod oblong, with slender beak. U. 
D. howellii Wats. 
NN. Petals 3—4 mm. long; pod ovate-lanceolate, with thick beak. C. E. 
D. lemmoni Wats. 
LL. Stems with few to many leaves above the caudex. C. 
D. aureola Wats. 
KK. Leaves keeled by the prominent mid-vein; plants densely caespitose, scapose. 
O. Leaf-hairs mostly simple; scapes woolly-hairy; pod broadly ovate, about 4 
times as long as the style. W.C.E. (D. ventosa.) 
D. densifolia Nutt. (Dense Whitlow-grass) 
OO. Leaf-hairs stellate; scapes glabrate or glabrous; pod ovate-oblong, 6—8 
times as long as the style. E. (D. glabella; D. glacialis.) 
D. saximontana Nels. (Rock Whitlow-grass) 
ATHYSANUS 
Annual, slender. Leaves basal, usually toothed, oblanceolate (ours). Flowers 
small, white, in long racemes. Petals small or none. Style very short. Pod orbicular, 
less than 2 mm. long (ours), hairy with hooked hairs (ours), not margined, indehiscent, 
flat, veinless, |-celled, I-seeded. (Gk. a—without, thysanos—=a fringe; because the pod 
is not wing-margined.) W.E. A, pusillus Gr. 
THYSANOCARPUS LACE-POD 
Annual, slender, erect, sparingly branched. Basal leaves toothed or pinnatifid. 
Flowers minute, white or rose, in long racemes. Petals minute. Pod orbicular, wing- 

