42 CRUCIFER/E. ARABIS. 



6 ARABIS L. Gen. n. 818. 



Annual biennial or perennial herbs, rarely suffruteseent at base 

 with usually simple leaves, stellate or forked pubescence, and 

 white or purple flowers in ebracteate racemes. Sepals equal or 

 the lateral ones saccate, at base. Petals entire or emarginate, 

 usually unguiculate. Stamens 6, free and unappendaged. Pods 

 linear compressed parallel to the partition, with flat or subcon- 

 vex, more or less prominently 1 -nerved valves and membranace- 

 ous partition. Stigma simple or barely 2-lobed. Seeds in 1-2 

 rows : elliptical or orbicular, more or less margined or winged. 

 Cotyledons accumbent or oblique. 



1 SISYMBRINA Watson in Gray Syn. Fl. i, 159. Bienni- 

 als or perennials with the pubescence, if any, wholly simple 

 above,, but forked upon the lowest leaves. 



A. Xuttallii Robinson in Gray Syn. Fl. i, 160. A. spathulata Nutt. T. & 

 G. FL i, 81, not DC. Stems slender simple, 6-10 inches high from a 

 branching biennial or perennial rootstock, erect or ascending, glabrous 

 above, more or less hirsute below : radical leaves spatulate-oblanceolate, 

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

 elliptical, sessile but not auricled: petals 2-3 lines long, white: pods short, 

 6-9 lines long by % of a line broad, somewhat attenuate to a rather stout 

 style: valves slightly convex, 1-nerved and faintly veined: seeds elliptical : 

 cotyledons accumbent. On low grounds, mountains of eastern Washing- 

 ton and western Montana. 



2 TURBITIS Flowers whitish ; pods narrow : seeds in 2 rows 

 in the cells. 



A. perfoliata Lam. Encycl. i, 219. Glaucous, stems erect, solitary, sim- 

 ple or sparingly branched, usually stout, 1-6 feet high from a biennial 

 root: radical leaves spatulate, 2-4 inches long, sinuate-pinnatifid or 

 toothed, ciliate and more or less hirsute with stellate hairs ; cauline leaves 

 entire ovate to ovate-lanceolate, clasping by the sagittate base : raceme 

 long .and strict: flowers white or stramineous: petals linear-lanceolate, 2- 

 3 lines long, not more than twice the length of the sepals: pods strictly 

 erect almost terete, 3-4 inches long, less than a line wide, on short pedi- 

 cels: style short or none, stigma 2-lobed : seeds somewhat in 2 rows nar- 

 rowly winged or wingless: cotyledons accumbent to incumbent in the 

 same pod. On dry ridges and stony hillsides, Brit. Columbia to Califor- 

 nia and across the continent to New England and New Jersey. 



3 EUARABIS Watson in Gray Syn. Fl. i, 160 in part. Seeds 

 orbicular or broadly elliptical, more or less wing-margined. Coty- 

 ledons tetrictly accumbent. 



A. hirsnta Scop. Fl. Cam. ed. 2, ii, 30. More or less hirsute at least at 

 the base with spreading simple or forked, rarely stellate hairs : stems often 

 clustered on the crown of the biennial root or branching caudex, 6-20 

 inches high,, simple or with slender strict branches above : radical leaves in 

 a rosulate cluster, ovate to- spatulate attenuate to a winged petiole, entire 

 or sparsely dentate; cauline ones ovate to oblong or lanceolate sessile and 

 partly clasping by a somewhat sagittate or cordate base : petals white, 

 spatulate twice as long as the greenish sepals : pods strictly erect 1-2 

 inches long, less than a line wide on erect slender pedicels ; style very 

 sfrort and stout or the stigma nearly sessile : seeds suborbicular, very nar- 

 rowly winged. In moist places, Sierra Nevadas of California through Ore- 

 gon and Washington to northern Alaska and across the continent to the 



