368 MISC. PUBLICATION 4 2 3, IT. S. DEPT. OF AGRICULTURE 



forests or open slopes in spruce-fir forests, May to July. Southern 

 Labrador to Yukon Territory, south to New Jersey, northern Arizona, 

 and California. 



4. Arabis tricornuta Rollins, Wash. Acad. Sci. Jour. 29: 478. 1939. 

 Rincon and Santa Rita Mountains (Pima County), possibly also in 



the Chiricahua Mountains (Cochise County), 7,000 to 9,000 feet, 

 August and September, type from the Rincon Mountains (Blumer 

 3478) . Known only from southern Arizona. 



This species is of particular interest because of the superficial 

 resemblance at flowering time to Pennellia micrantha. The flowers 

 are small and in long, loose, very narrow racemes. 



5. Arabis pulchra M. E. Jones ex S. Wats., Amer. Acad. Arts and 



Sci. Proc. 22: 468. 1887. 



The species is represented in Arizona by var. pattens M. E. Jones 

 (A. jormosa Greene), which has been collected at Kayenta (Navajo 

 County), about 6,000 feet, sandy hillsides and open knolls among 

 sagebrush, pinyon, and juniper, May to July. This variety occurs in 

 the Colorado River drainage area in western Colorado, eastern Utah, 

 and northeastern Arizona. 



Other varieties of Arabis pulchra have not been collected in 

 Arizona, but A. pulchra var. munciensis is known from a local- 

 ity between St. George and the Beaver Dam Mountains, in ad- 

 jacent Utah. This variety is distinguished from var. pollens by 

 having spreading pedicels, pendulous siliques, and smaller, purple 

 instead of white or pink flowers. Among Arizona species of Arabis, 

 A. pulchra is unique in having relatively large, showy flowers and 

 finely pubescent siliques. 



6. Arabis gracilipes Greene, Pittonia 4: 193. 1900. 



Arabis arcuata (Nutt.) A. Gray var. longipes S. Wats, in A. 



Gray, Syn. Fl. North Amer. 1: 164. 1897. 

 Arabis perennans S. Wats. var. longipes (S. Wats.) Jepson, Fl. 



Calif. 2: 70. 1936. 



Coconino, Mohave, Gila, and Yavapai Counties, hot sandy canyons 

 and lower mountain slopes, rarely collected, April to June, type of A. 

 gracilipes from near Flagstaff (N. C. Wilson in 1893), type of A. 

 arcuata var. longipes from near Fort Mohave (Lemmon in 1884). 

 Known only from Arizona, 



Arabis gracilipes is related to both A. perennans and A. fendleri, 

 but is readily separated from them by the robust habit, numerous 

 large cauline leaves, very long filiform pedicels, and usually solitary 

 stems. 



7. Arabis lignifera A. Nels., Torrey Bot. Club Bui. 24: 123. 1899. 

 Twelve miles east of Keam Canyon, Navajo County (Peebles and 



Smith 13438), the only collection known from Arizona, about 6,000 

 feet, sandy or stony soils, often among sagebrush, pinon, or juniper, 

 April and May. Wyoming to Idaho, south to Colorado, northeastern 

 Arizona, and Nevada. 



This species has something of the habit of A. perennans, but differs 

 markedly in having short rigid recurved pedicels, fewer stems, and a 



