CRUCIFERAE (MUSTARD FAMILY) 229 



siliques glabrous, linear, somewhat curved, reflexed or pendent, on short 

 widely spreading pedicels: seeds in 1 irregular row. On naked limestone 

 slopes; southeastern Wyoming to Colorado. 



21. Arabis Fendleri (Gray) Greene, Pitt. 3: 156. 1897. Related to the 

 foregoing, with similar pubescence: stem mostly solitary, erect, 3-5 dm. high, 

 glabrous above: basal leaves few, oblanceolate, similar to the lower cauline 

 which are equably distributed, with hirsute-ciliate and scattered trifurcate 

 hairs, tapering to a slender petiole, rarely 3 cm. long; the upper cauline re- 

 duced, glabrous, auriculate-clasping: siliques as in the preceding but longer: 

 seeds in 2 rows. Colorado to New Mexico. 



22. Arabis caduca A. Xels. Biennial, maturing early the second season and 

 then quickly disintegrating: stems solitary from a taproot, erect, thick but 

 brittle, branched above, hirsute with branched hairs at base only: basal leaves 

 rosulate, early caducous, oblanceolate, petioled, 2-3 cm. long, rough with a 

 branched hirsute pubescence; cauline oblong or broadly linear, sessile by an 

 auricled base, glabrous: flowers small; racemes becoming very long, rather 

 crowded: siliques 1-nerved to the middle, broadly linear, straight, acute, gla- 

 brous, 5-7 cm. long, pendent on reflexed pedicels, or more usually on pedicels 

 sharply refracted at their has;- seeds in 2 rows. .1 . Holbodlii in part. Sandy 

 slopes and plains; southern Wyoming, south and west to Utah. 



23. Arabis lignipes A. Xels. Bot. Gaz. 30: 191. 1900. Short lived peren- 

 nial: stem usually solitary, virgate, and simple (rarely 2 or 3 from the crown), 

 3-5 dm. high, cinereously stellate-pubescent below (often only the raceme 

 glabrous), lignescent at base, a short portion persisting each year (for 2 or 

 3 years) and this part crowned with a rosulate cluster of leaves, from among 

 which rises, proliferous, the next year's stem: lower leaves oblanceolate-linear, 

 cinereous-stellate, subpetioled, 2-4 cm. long; upper cauline sessile, auriculate, 

 lanceolate, often glabrous: raceme long and narrow: sepals purplish, scarious- 

 margined, exceeded by the white or pale petals: siliques very slender, curved, 

 becoming 6 cm. or more in length, pendent on slender pedicels, usually 

 sharply refracted: seeds in 1 row. From noil hern Wyoming to Utah. 



24. Arabis lignifera A. Xels. Bull. Torr. Bot. Club 26: 123. 1st 19. Branched 

 from the base and decidedly woody-persistent, 3-5 dm. high: annual stems 

 several, assurgent or erect, simple or branched, suhstellate below, glabrous 

 above: leaves finely stellate, mostly basal, on short sterile branchlets, oblong- 

 oblanceolate, petioled, 3-5 cm. long; cauline from oblong to lanceolate, short- 

 auriculate: raceme simple or branched, nearly or quite glabrous: petals white 

 or pinkish, twice as long as the obtuse scarious-margined sepals: siliques 

 linear, 3-4 cm. long, from widely divaricate to pendulous; the valves 1-nerved: 

 seeds uniseriate, as broad as the valves, narrowly winged. Arid canon-sides; 

 southwestern Wyoming to Colorado and I'tah. 



25. Arabis Selbyi Rydb. Bull. Torr. Bot. Club 31: 257. 1904. Perennial 

 with a basal rosette of oblanceolate, acute, sinuate-denticulate, short petioled 

 leaves, 5-10 cm. long and green but stellate on both sides: stems branched, 

 4-5 dm. high: cauline leaves linear-lanceolate, sagittate at the base: raceme 

 long and lax: sepals linear, sparingly stellate': petals red-purple, long-clawed: 

 silique divergent, broadly linear, 3 cm. long, on short divergent pedicels: 

 seeds in 2 rows. Southwestern Colorado. 



26. Arabis eremophila Greene, Pitt. 4: 194. 1900. Perennial, the herbage 

 cinereous with a rather dense branched pubescence : stems several from the 

 base, ascending, 1-3 dm. long: leaves mostly basal, oblong-lanceolate, sa- 

 liently denticulate, petioled; cauline few, linear, with short and inconspicuous 

 auricles: petals rose-red, small: siliques narrowly linear, 3-4 cm. long, spread- 

 ing, on slender pedicels nearly half as long: seeds in 1 row. Southern Col- 

 orado to Xew Mexico and Arizona. 



24. ERYSIMUM L. WESTERN WALLFLOWER 



Biennials or perennials, with short harsh pubescence of branched hairs, 

 alternate, entire or toothed leaves (not clasping at base), and flowers generally 



