310 BRASSICACEAE 



simple 15-30 cm. high, sparsely pubescent with 3-forked hairs. Basal leaves oblanceolate, 10-15 

 mm long, pale, stellate with 3-forked hairs; stem leaves oblong, 10-12 mm. long auriculate, gla- 

 brous or nearly so, pods straight, ascending on rather long diverging pedicels, 2.5-5 cm. long, 1.5 

 mm. wide, narrowed at apex to a slender beak, the valves smooth with no trace of a midrib; 

 seeds in l'row, oval, narrowly winged at the upper end. 



Dry rocky slopes, Boreal Zones; Cascade Mountains, Oregon. Type locality: Mount Thielson, Cascade 

 Mountains, Oregon. June-Sept. 



19. Arabis microphylla Nutt. Small-leaved Rock-cress. Fig. 2115. 



Arabis microphylla Nutt. in Torr. & Gray. Fl. N. Amer. 1: 82. 1838. 

 Arabis tenuicula Greene, Leaflets Bot. Obs. 2: 82. 1910. 



Perennial, with a slender branching caudex, the stems several, erect, 1-3 dm. high, very 

 slender somewhat stellate at base or glabrous. Leaves oblanceolate or spatulate, 5-30 mm. long, 

 entire densely stellate-pubescent ; petals usually white, 3 mm. long ; fruiting pedicels 5-10 mm. 

 long, ascending; pods ascending, 2-4 cm. long, 1-1.5 mm. wide; style obsolete; seeds in 1 row, 

 slightly winged at apex. 



Dry mountain slopes, mainly Arid Transition Zone; Klickitat County, Washington, and Wasco County, 

 Oregon, to Montana, Utah, and Nevada. Type locality: "Rocky Mountains." June-Sept. 



20. Arabis platysperma A. Gray. Broad-seeded Rock-cress. Fig. 2116. 



Arabis platysperma A. Gray, Proc. Amer. Acad. 6: 519. 1865. 

 Arabis oligantha Greene, Rep. Nov. Spec. 5: 243. 1908. 



Perennial with a branching rootstock, glaucous, more or less stellate throughout, the stems 

 erect or ascending, 5-30 cm. high, simple or branched. Leaves all entire, the basal leaves oblan- 

 ceolate, 2-3 cm. long, those of the stem oblong-lanceolate to linear-lanceolate, sessile; petals 

 nearly white to rose, 4-6 mm. long ; pedicels 5-15 mm. long ; pods erect or a little spreading, 25- 

 60 mm. long, 3-5 mm. wide ; seeds orbicular, broadly winged. 



Rocky or gravelly soils, Arid Transition and Canadian Zones; North Coast Ranges and Sierra Nevada to 

 the San Jacinto Mountains, California. Type locality: "Sierra Nevada, on Mount Dana, alt. 13,227 feet, and 

 above Ebbett's Pass," California. June-Aug. 



Arabis inamoena Greene, Rep. Nov. Spec. 5: 243. 1908. Perennial, with a cespitose caudex, the flower- 

 ing stems 10-25 cm. high, pubescent below with forked hairs, sparsely so above. Basal leaves oblanceolate, 10-25 

 mm long 2-4 mm. wide, stellate-oubescent; stem leaves several, oblong, 5-15 mm. long, stellate-pubescent, not 

 auriculate- racemes 3-4-flowered; pedicels 3-5 mm. long, sparsely pubescent or glabrous; sepals scarcely 3 mm. 

 long sparsely pubescent; petals white, 3 mm. long; pods erect, nearly 4 mm. wide, 4-5 cm. long glabrous; 

 seeds in 1 row orbicular, broadly winged. Alpine slopes, Hudsonian Zone; southern Sierra Nevada, California. 

 Type locality: Long Meadow, Tulare County, California. Doubtfully distinct from Arabis platysperma A. Cray. 



21. Arabis Howellii S. Wats. Howell's Rock-cress. Fig. 2117. 



Arabis Howellii S. Wats. Proc. Amer. Acad. 25: 124. 1890. 



Arabis platyloba Greene, Pittonia 4: 198. 1900. 



Arabis Leibergii Greene, Rep. Nov. Spec. 5: 243. 1908. 



Arabis platysperma var. Howellii Jepson, Man. Fl. PI. Calif. 432. 1925. 



Perennial with a much branched cespitose caudex, glabrous except for a few cilia on the 

 petioles; stems 3-15 cm. high, simple or branched. Leaves all narrowly oblanceolate, 15-25 mm. 

 long acute or obtuse, entire, glaucous, those of the stem somewhat clasping and more or less 

 auriculate or cordate ; petals rose-colored ; pods erect, 3-5 cm. long, 4-5 mm. broad, acuminate ; 

 stigma sessile ; seeds orbicular, broadly winged all around. 



Summits of high peaks, Boreal Zones; Mount Hood, Oregon, south through the Cascade Mountains and 

 the northern Sierra Nevada, California. Type locality: Ashland Butte, Jackson County, Oregon. June-Aug. 



22. Arabis Covillei Greene. Coville's Rock-cress. Fig. 2118. 



Arabis Covillei Greene, Rep. Nov. Spec. 5: 243. 1908. 

 Arabis conferta Greene, loc. cit. 



Perennial with a branching rootstock, glabrous throughout except for a few cilia on the leaf 

 bases, the stems somewhat tufted, simple or branched, including the fruiting pods 6-20 cm high. 

 Basal leaves oblanceolate to narrowly so, 15-25 mm. long; stem leaves usually 2-4, oblong, 

 sessile, 6-12 mm. long; petals rose-purple or sometimes white, 4-5 mm. long; pods 4-6 cm. long, 

 4 mm.' wide ; seeds in 1 row, strongly winged all around. 



Alpine slopes, Canadian Zone; central and southern Sierra Nevada, California, and the Washoe Mountains, 

 Nevada. Type locality: near the lake on trail to White Chief Mine, 1,000 feet above Mineral King, Tulare 

 County, California. July-Aug. 



23. Arabis Parishii S. Wats. Parish's Rock-cress. Fig. 2119. 



Arabis Parishii S. Wats. Proc. Amer. Acad. 22: 468. 1887. 



Perennial, with a cespitose much branched caudex, finely stellate-pubescent throughout, the 

 stems simple, 5-10 cm. high, slender. Basal leaves numerous, linear-oblanceolate, 5-15 mm. long, 

 entire ; stem leaves few, linear, sessile, not auriculate ; sepals purplish, 3-4 mm. long ; petals rose- 

 colored, 6-8 mm. long ; fruiting pedicels 4-6 mm. long ; pods ascending, 2 cm. long, 2 mm. wide, 

 attenuate at apex; style filiform, 4-6 mm. long; seeds elliptical, narrowly winged, somewhat 

 in 2 rows. 



Gravelly slopes, Arid Transition and Canadian Zones; San Bernardino Mountains, California. Type 

 locality: Bear Valley, 6,500 feet altitude. May-July. 



