MUSTARD FAMILY 71 



scarcely auriculate; flowers few; petals purplish, 3 lines long; pods linear, very 

 acute or attenuate-acute at apex, 1 14 to 2 inches long, li/^ to 3 lines broad, pendu- 

 lous on pedicels 4 to 9 lines long; valves 1-nerved, veined; seeds in 2 rows. 



Dry or stony situations, 5500 to 6500 feet : east or north of the Sierra Nevada 

 crest from Nevada Co. to Siskiyou Co. North to Washington. Rarely collected 

 in California. 



Loes. — Truckee, Sonne 9 ; Shackelford Creek, w. Siskiyou Co., Butler 1705. 



Eefs. — Arabis suffrutescens "Wats. Proc. Am. Aead. 17:362 (1882), type loc. Snake 

 Eiver, Union Co., Ore., CusicTc ; Jepson, Man. 432 (1925). 



21. A. glaucovalvula Jones. Mesa Rock-cress. Stems several from a branch- 

 ing woody crown, branched above, 7 to 14 inches high; herbage canescent; leaves 

 mostly basal, these with blades oblanceolate, entire, and gradually narrowed to a 

 petiole, the whole 1 to 2^/2 inches long, the cauline few, their blades linear to lance- 

 olate, reduced and sessile; flowers rather large, purple, in one-sided racemes; sepals 

 ovate, woolly-pubescent with scarious margins; pods deflexed, glabrous, glaucous, 

 narrow-oblong, rounded at each end, 1-nerved and veiny, 1^ to 1% inches long, 

 ^ inch wide, on pedicels 2 to 4 lines long; style stout and rather prominent; seeds 

 in 2 rows with broad membranous wings, 2 lines broad. 



Gravelly mesas, 2200 to 5000 feet: eastern Mohave Desert; Inyo Co. East to 

 Nevada. Mar. 



Locs. — Shay's Well, w. of Warren's Well, Jepson 5958; Cima, K. Brandegee ; MeGee Mdws., 

 Bishop, Inyo Co., K. Brandegee. Nevada: Fallon, Blanche Boss 28. 



Eefs. — Arabis glaucovalvtila Jones, Contrib. W. Bot. 8:40 (1898), type loc. Darwin Mesa, 

 Argus Mts., Jones; Jepson, Man. 432, fig. 419 (1925). 



22. A. nardina Greene. Canon Rock-cress. Stems several from the branched 

 root-crown, erect, 5 to 10 inches high, canescent; leaves mostly in a basal tuft, 

 hoary-canescent, the blades linear-oblanceolate, acute or acutish, 4 to 6 lines long, 

 gradually narrowed to a petiole half as long to rather longer; blades of cauline 

 leaves linear to narrow-oblanceolate, sessile; pedicels 1^^ to 4 lines long; pods 

 straight or a little curved, ascending, 1% to 2% inches long, 1^ lines wide ; seeds 

 broadly winged. 



Flats in desert caiions, 2000 to 3000 feet: south side of Mohave Desert; Pana- 

 mint Range. Apr. 



Locs. — North slope San Bernardino Mts., Parish 1300; Cactus Flat, Cushenbury Canon, 

 Jones. 



Eefs. — Arabis nardina Greene, Lflts. 2:70 (1910), type loc. MiE Creek, Panamint Eange, 

 Coville 4- Funston 776; the label on the type spm., no. 776 (U. S. Nat. Herb.), reads "Mill 

 Creek", whereas the record for no. 776 in Contrib. U. S. Nat. Herb. 4:250 is Willow Creek. 

 A. juniperina Jones, Contrib. W. Bot. 15:68 (1929), type loc. Cactus Flat, Cushenbury Canon, 

 San Bernardino Mts., Jones. 



Arabis dispar Jones, Contrib. W. Bot. 8:41 (1898), type loc. Pleasant Canon, Panamint 

 Eange, Jones; habit and leaves apparently similar to A. nardina Greene; "pods 3 inches long, 

 % line wide ; seeds not margined." 



23. A. platysperma Gray. Pioneer Rock-cress. (Fig. 138.) Stems erect 

 or ascending from a slender branching root-crown, 2^4 to 12 inches high; herbage 

 glaucous, finely pubescent or hispidulous or sometimes glabrous; blades of basal 

 leaves oblanceolate, narrowed to a short petiole, % to 1% inches long, the upper 

 leaf -blades oblong- to linear-lanceolate, sessile; petals at first white, changing to 

 rose-color, 2 to 3 lines long, the sepals % to nearly as long, glabrous, or hispid to- 

 wards apex; pods erect or a little spreading, 1 to 2 inches long, l^/^ to 2 lines broad, 

 tipped with a short stout style; valves distinctly veined, 1-nerved toward the base; 

 seeds in one row, orbicular, winged all around (or nearly so) with a broad scarious 

 membrane. 



