160 CRUCIFER.E. Arabb. 



mostly entire : petals white, 2 lines long : pods (immature) an inch long by two thirds Hue 

 wide, straight, abruptly tipped witli a very short thick style, ascending on slender pedicels 3 

 to 4 lines long; valves nearly nervelos (3-nerved ace. to V^ahl) : seeds in 2 rows; the "coty- 

 ledons incumbent." — Proc. Am. Acad. xxv. 124. Sisi/mhrimn humlfiisiim, Va.\il,Fl. l^nu. 

 t. 2297 • Lange, Medd. Gra'n. iii. 51. — Ungara Bay, N.Labrador, Turner. (Greenland.) 

 The cutylcdoDs arc said to be incumbent, but are represented only partially so in the figure. 

 Var. pubescens, Watsox, n. var. Lower leaves and base of the stem pubescent. — 

 York Factory, Bell, Macottn. The mature pods of this variety, which appears to differ only 

 in its pubescence from the Greenland form, have the valves distinctly nerved, and the nar- 

 row acute seeds with obliijue cotyledons, as represented. 

 A.* Nuttallii, Robinson, n. sp.^ Biennial or usually perennial with a branching rootstock : 

 stems simple and slender, a span high or less, erect or ascending, glabrous above, more or 

 less hirsute below with rather long simple and often forked hairs . radical leaves spatulate- 

 oblanceolate, acutish or obtuse, entire, an inch long or less ; cauline narrowly oblong to 

 elliptical, sessile ; petals 2 to 3 lines long, white : ])ods short, 6 to 9 lines long by one third 

 line wide, somewhat attenuate to a rather stout style; valves slightly convex, 1 -nerved and 

 faintly veined : seeds in 1 row, elliptical ; cotyledons accumbeut ! — A. s/iathtilata, tiutt. in 

 Torr. & Gray, Fl. i. 81 ; Brew. & Wats. Bot. Calif, i. 32 ; not DC. — iMountains of W. Mon- 

 tana to N. Utah, N. Nevada, and E. Washington, chiefly on low ground in valleys, 

 -i— -I— Cauline leaves auriculate. 

 A. Hookeri, Lange. Stems several from a biennial (or perennial ? ) branching rootstock, 

 slender, ascending, branched, a span high, hirsute below with simple or forked hairs : radical 

 leaves oblanceolate, acute, sinuate-dentate, 2 inches long or less, rather densely hirsute with 

 short forked hairs ; petioles ciliate ; cauline leaves lanceolate to linear with a cla.«ping sagit- 

 tate base, mostly entire : sepals and pedicels hairy : petals white, 2 lines long : pods 1 to \\ 

 inches long by tliree fourths line broad, somewhat attenuate to a very short thick style, 

 ascending or spreading upon spreading pedicels 3 to 6 lines long; valves 1-nerved; seeds in 

 2 rows, minute, oblong; cotyledons incumbent thougli slightly oblique. — Medd. Green, iii. 

 50. Turiitis mollis, Hook. Fl. Bor.-Am. i. 40; Horuem Fl. Dan. t. 2296. — Shore of the 

 Arctic Sea between 107° and 130° W. longitude, Iiicluirdso)i. (Greenland.) 

 A. dentata, Torr. & Gray. Biennial, branching from the base, pubescent throughout with 

 fine mostly stellate pubescence : stems lax, ascending or decumbent, 1 to 2 feet long : leaves 

 all acutely and irregularly dentate, very rarely the lower lyrate-pinnatifid ; the radical petio 

 late, obovate to oblanceolate : flowers very small and nearly sessile ; petals white, a line 

 long: pods very narrow, nearly straight, widely spreading, 8 to 12 lines long, glabrous, on 

 pedicels an inch long, beaked by a very short thick style ; valves very faintly l-nerved at 

 base; seeds oblong, in 1 row, wingless, minute; cotyledons obliiiue. — Fl. i. 80; Torr. Fl. 

 TSf. Y. i. 54, t. 7. Sisymbrium dentalum, Torr. in Short, PI. Kentucky, 3d Suppl. 338. — New 

 York to Michigan and Minnesota, south to the Potomac, Tennessee, and Mis.souri. 

 A. perfoliata, Lam. (Tower Mistard.) Glaucous: stem erect, solitary, simple, usually 

 stout and 2 to 5 feet high, commonly hairy near the base: radical leaves lyratcly ]jinnatifid 

 to sjiatulate-oblanceolate and tootlied, usually more or less hirsute or coarsely stcdlate-pubes- 

 cent ; cauline glabrous, entire or the lower toothed, lanceolate to oblong, auricled at base, 

 1 to 4 inches long: petals yellowish white, 2 to 3 lines long: fruiting pedicels 2 to 6 

 lines in length : pods strictly erect, 1 J to 4 inches long by one half to two thirds line wide, 

 beaked with a short stout style or the broad scarcely 2-lobed or cupulate stigma nearly 

 sessile; valves rather rigid, 1-nerved and veined; seeds crowded, irregular, somewhat tur- 

 gid, nearly marginless ; cotyledons partially incumbent — Diet. i. 219. Turritis ghhra, 

 L. Spec. ii. 666. T. macrocarpn, Nntt. in Torr. & Gray, Fl. i. 78. — From the Lower St. 

 Lawrence through New England (where infrequent) to New Jersey and westward to the 

 SaskatcheAvan, south in the Rocky Mts. to Colorado and N. Utah ; on the Pacific Slope from 

 Oregon to S. California. (L. Calif., Eu., Asia.) The cotyledons vary from accumbent to 

 incumbent in the same pod. 



§ 2. EuARABis. Seeds in one row, at least when mature, orbicular or broadly 

 elliptical, more 6r less wing-margined ; cotyledons strictly accumbent. 



1 The name of this species has been altered on account of tha older and still valid homonym. 



