Arabis. CRUCIFER.E. 159 



44. Arabis, L. Rock Ckess. (Xame from the country Arnhki.) — 

 Aimiiiils or perennials mostly of erect habit, nearly all of the Northern Tem- 

 perate and Arctic Zones. Pubescence branched or stellate, rarely simple or 

 none. Flowers white, purple, or more rarely stramineous, in more or less elon- 

 gated racemes. Leaves mostly lanceolate or spatulate, entire, dentate, or less 

 frequently pinnatifid. — Gen. no. o44 ; DC. Syst. ii. 213; Keichenb. Ic. Fj. 

 Germ. ii. t. 3;J-4-i ; Gray, Gen. 111. i. o8 ; Iknlli. it llouk. (Jen. i. G'J. Tar- 

 ritU, L. Gen, no. o4G. [By 8. Watsux.] 



§ 1. SiSYMBufxA, Watson.^ Seeds oblong or elliptical, very small, wing- 

 less ; cotyledons often more or less oblique. Jiiennial or [)erennial. rubescenee, 

 if any, usually simple upon the upper parts, but invarialjly forked to some extent 

 when present upon the lowest leaves. 



* Leaves all i)iiiii:itely (livided , scsj^imMits lilifonn. 

 A.* filifolia, (iRKKXE. A delicate glal)i(>u.s somewhat glaiuous aiiuual, 8 iiiclies to a foot in 

 heii;lit, stem Hexuoiis or somewhat genic-ulate and hranched ahove : flowers roseate or 

 pnrple : ])etals ohovate, jjatulous, 2 to 3 lines in length, about twice the length of the cakx ; 

 pods narrowly linear, acute, about 15 lines in length, spreading-ascending. — Bull. Calif. 

 Acad. Sci. ii. 390, Carclamine Jihfolia, Greene, Pittonia, i. 30. — Santa Cruz IsL, Calif., 

 Greene, Braiidefjee. A species of doubtful position. Mature seeds have not been seen. ^1, 

 pectlnata, Greene, Tittonia, i. 287, of Lower California, is nearly related. 

 * * Radical leaves lyrately pinnatifid , segments short and bruad ; cauline not auriculate 

 at tlie base. 

 A. lyrata, L. slender, brandling from the base, glabrous or rarely somewhat hairy at the 

 base : the stems ascending, a foot high or less : basal leaves with few and small lateral seg- 

 ments or pinuately lobcd, often all entire, oblanceolate or spatulate to linear: petals white 

 or pinkish, 2 to 4 lines long , pods ascending on slender pedicels 3 to 6 lines long, very nar- 

 row with a short stout style, straight or slightly curved; the valves ratiier thick, firm, and 

 nerved nearly to the top. — Spec. ii. 665, A. pelnm. Gray, Man. ed. 5, 67, in part. Hisyni- 

 biinm arabldonlis, Hook, Fl. Bor.-Am i. 63, t. 21, at least in part. Cunlumiuc spathuUila, 

 Michx. Fl. ii. 29. — From the Great Lakes to Connecticut and New .Jersey, and southward 

 along the Alleghanies to N. Carolina and Tennessee.- Southward it becomes decidedly 

 perennial, with more lax and slender stems, and the pods with thinner and scarcely nerved 

 valves. No seeds have been examined with cotyledons so strictly incuml)ent as figured and 

 described Ijy Hooker. 



Var. OCcidentalis, Watson, n. var. Pods with sessile .stigma or a very short and 

 thick style ; tlie valves rather tliin but often faintly nerved to the top. — .1. amhitjua, DC. 

 Syst. ii. 231, in part; Torr. & Gray, Fl. i. 81. A. petnra, var., Regel, Bull, Soc. Nat, Mo.sc. 

 XXXV. pt. 2, 163. —From Alaska to British Columbia and the eastern .side of the Rocky 

 Mts. in Brit. America; l\)int Peloc on Lake Krio, .]r<iroini. (Kamtschatka, \Vn';iht.) The 

 true ^1. petrmt. Lam., as it occurs in Eurojje, appears to l)e distin-juished from all American 

 forms by its usually broader and blunter pod, more broadly elliptical or noarlv orbicular 

 seed, and the cotyledons strictly accumbent. The Greenhunl specimens referred to this 

 species as a variety, with pilose siliques and pedicels (Lange, Mcdd. Gra'u. iii, 49), are more 

 probaI)ly the same as Hooker's Sisi/mhrinin humile. 



* * * Radical leaves oblanceolate, toothed or entire. 

 -I— Cauline leaves not auriculate. 

 A. humifusa, Watson. Glabrous, branching from the Imse : the low decumbent stems 6 

 inches high or less, simple or l)r:inched : radical leaves usually numerous, few-toothed, an 

 inch loni: or less , the petioles rarely slightly ciliate ; cauline leaves spatulate-oblanceolate, 



1 /'.-..(/(/a/niJA-, Wats, in Cray, Man, e.l, 6, 67, & Proc. Am. Arad. xxv. 121, Vmt not of Endl,, 

 wliirli, lifing Pseudoarahls of C. A IMeyt-r, dcpenils upon a <hti'ercnt siibdivi.siou of tlif -<iuis. 

 - S. Missouri, Eggert, 



