MUSTARD FAMILY 69 



Man. 429, fig. 416 (1925). Probably A. duriuscula Greene, Pitt. 4:191 (1900), type loc. Donner 

 Lake, Michener. 



A. NEMOPHiLA Greene, Lflts. 2:78 (1910), type loc. Sequoia National Forest, A. Davidson. 

 Petals white or pinkish; pods straight, extremely narrow, 3 inches long, erect (ex char.). — This 

 may be a form of A. rectissima Greene ; or, yet again, it might be A. drummondii Gray. 



17. A. arcuata Gray. Curly Rock-cress. Stems usually simple and erect, 1 

 to 3I/2 feet high from the simple or branching crown of a perennial root; herbage 

 stellate-pubescent, the leaves stellate-canescent ; blades of basal leaves linear-ob- 

 lanceolate, mostly acute, entire or repand-dentate, 1 to IY2 or 2^4 inches long, the 

 petioles often ciliate; blades of cauline leaves linear to lanceolate, mostly entire; 

 corolla 3 to 5 lines long, mostly dark red; pods commonly curved or sometimes 

 nearly straight, glabrous, 2 to 4 inches long, % to 1% lines wide, acute, spreading 

 or defiexed on divaricate pubescent or canescent pedicels 2 to 5 lines long. 



Mountains, 2500 to 6000 feet: Sierra Nevada from Shasta Co. to Tulare Co.; 

 intermontane and cismontane Southern California. South into Lower California. 

 May-June. 



Habit note. — The root-crown or caudex remains simple the first two or three years, after 

 which it develops few to several short persistent woody branches which bear the flowering stems 

 of the season. These stems are usually densely leafy at base. In habit and in most features 

 as well this species is most closely related to A. perennans Wats. 



Locs. — Sierra Nevada: Horse Mt., Shasta Co., J. T. Howell 2311 (pedicels subglabrous) ; 

 Folsom, Alice King; Snow Creek, Mariposa Co., Jepson 10,487; Yosemite, Jepson 4271; Mari- 

 posa, Congdon; Huntington Lake, A. L. Grant 1060; Dunlap to Millwood, Fresno Co., Jepson 

 2772 ; Cedar Creek, Sequoia Park, Jepson 600 ; Kaweah, Sopping 381. S. Cal. : Redreef Canon, 

 Topatopa Mts., Abrams ^ McGregor ; Echo Mt., San Gabriel Mts., Peirson 62; San Bernardino, 

 Parish 4387 ; Strawberry Valley, Mt. San Jacinto, Jepson 1287 ; Idyllwild-Keen Camp road, C. V. 

 Meyer 169; Witch Creek, Alder son; Campo, Abrams 3563. 



Var. rubicundula Jepson var. n. Leaves less pubescent; corolla pale pink; pedicels short- 

 pilose. — (Folia minus pubescentia; petala rubicundula; pedicelli breviter pilosi.) — Mt. Day, 

 Santa Clara Co., R. J. Smith (type). 



Eefs. — Arabis aucuata Gray, Proc. Am. Acad. 6:187 (1864). Streptanthus arcuatus Nutt.; 

 T. & G. Fl. 1:77 (1838), type loc. high hills, Santa Barbara, Nuttall. A. holboellii var. arcuata 

 Jepson, Man. 430, fig. 417 (1925). A. maxima Greene, Pitt. 4:192 (1900). Var. rubicundxila 

 Jepson. 



18. A. pulchra Jones. Desert Rock-cress. Stems one or several from a 

 branching woody crown, erect, commonly simple, leafy, 12 to 15 inches high; herb- 

 age stellate-canescent or -pubescent throughout; blades of lower leaves narrow- 

 oblanceolate, gradually contracted below to a petiole, the whole 1 to 2% inches 

 long, blades of the upper leaves linear-lanceolate, sessile; raceme not very dense; 

 flowers usually large, soon spreading or reflexed; petals 4 to 6 lines long, rose-color, 

 about twice as long as the pubescent sepals; ovary usually densely woolly; pods 

 pendent, finely pubescent or glabrate, II/2 to 2% inches long, 11/2 lines wide, on 

 defiexed pedicels 4 to 7 lines long; stigma sessile; valves longitudinally veined on 

 either side of the midnerve; seeds small, in 2 rows, orbicular, narrowly winged. 



Dry soil or slate rocks, 2000 to 5500 feet : desert slopes of mountains on the 

 western borders of the Mohave and Colorado deserts; desert ranges; east side of 

 the Sierra Nevada. East to Utah. Mar.-May. 



Tax. note. — There is a gross similarity in habit between the flowering stages of Arabis 

 pulchra and Arabis arcuata. In A. pulchra, however, the pedicels are usually deflexed from the 

 beginning and the ovaries white-tomentulose ; in A. arcuata the pedicels are commonly divari- 

 cate and the ovaries commonly glabrous or at most only partially puberulent. It is thus possible 

 to distinguish provisionally the two species without the presence of fruits. The ranges of these 

 two species meet, but are mutually exclusive, A. pulchra being of the deserts, A. arcuata being 

 chiefly of the Arid Transition Zone in cismontane California. 



Locs.— Jacumba, Abrams 3643; Cushenbury Canon, Parish 2323; Hesperia, Parish 2323a; 

 Acton, Basse; Lancaster, Davidson; Fairmont, Antelope Valley, Dudley # Lamb; Mt. Pj^oS; 

 Abrams 4- McGregor 202; Ft. Tejon, Parish 1969; San Emigdio Canon, Kern Co., Davy 2016; 

 Oak Canon, Tehachapi Mts., Dudley 425; Walker Pass (e. slope), Abrams 11,936; Granite Wells, 



