FLOWERING PLANTS AND FERNS OF ARIZONA 549 



E. L. Greene published Toxicodendron arizonicum, T. laetevirens, 



and T. pumilum, based on Arizona types, but these arc probably only 

 individual variations. A form with seeds constricted at the side 

 Toxicodendron divaricaium Greene (T. radicans var. dwaricatum 

 Barkley), was collected near Bisbee, Cochise County (Goodding 46). 

 Poison-ivy, poison-oak. A variable, often climbing plant, con- 

 taining a nearly nonvolatile oil, urushiol, that causes painful swelling 

 and eruption of the skin with many persons. The milk}* juice is 

 poisonous when taken internally. 



2. Rhus ovata S. Wats., Amer. Acad. Arts and Sci. Proc. 20: 358. 1885. 

 Hualpai Mountain (Mohave County) to Gila and eastern Maricopa 



Counties, 3,000 to 5,000 feet, slopes and mesas, common in chaparral, 

 April. Central Arizona, southern California, and Baja California. 

 Sugarbush, sometimes called mountain-laurel in Arizona. A hand- 

 some shrub, cultivated as an ornamental in California, with bright 

 green, somewhat shiny, leathery, entire leaves, deep-red flower buds, 

 and cream-colored flowers. The shrubs reach a height of at least 4.5 

 m. (15 feet). The old bark is very shaggy. 



3. Rhus kearneyi Barkley, Mo. Bot. Gard. Ann. 24: 363. 1937. 

 Tina j as Altas, southern Yuma County {Goldman 2311, Kearney 



and Harrison 6573, the type collection), dry cliffs. Known only from 

 tin's locality. 



4. Rhus trilobata Xutt. ex Torr. and Gray, Fl. North Amer. 1: 219. 



1838. 



Throughout the State, 2.500 to 7,500 feet, very common on slopes 

 and in canyons, often in chaparral, March to June (August). Saskatch- 

 ewan to \Yashington, south to Mexico. 



Squawbush, skunkbush, etc. A polymorphic species with aroma- 

 tic foliage, yellow flowers, and bright red fruits. In addition to the 

 typical form, the most distinct forms in Arizona are: (1) var. pit 

 sirna Engler {Rhus emoryi Wooton), with velvety villous herbage and 

 fruits, common in the central and southern parts of the State, usually 

 flowering in March; (2) var. simplicifolia (Greene) Munz and Sloane. 

 with leaves reduced to a single leaflet or the lateral leaflets very small. 

 Apache County to eastern Mohave County; and (3) var. racemulosa 

 (Greene) Munz and Sloane, with exceptionally long pedicels and 

 flowering in late summer, after the leaves have matured, whereas the 

 other forms usually flower in advance of the leaves. Tins last form 

 is confined to the mountains of Greenlee, Cochise, and Pima Counties, 

 5.000 to 6,000 feet. Several other segregate species were published 

 by Greene, based on Arizona types, but these probably represent 

 mere individual variations. 



The plants are browsed The Indians used the pliable steins in 

 basketry and ate the berries, also using them as a mordant in dyes. 



5. Rhus glabra L.,Sp. PI. 265. 1753. 



Rhus cismontana Greene, Wash. Acad. Sci. Proc. 8: 189. 1906. 



Apache County to Coconino County, south to Cochise and Pima 

 Counties, 5,000 to 7,000 feet, common in rich soil, often forming 

 thickets, ascending to the yellow pine belt, June and July. Canada to 

 Florida, New Mexico, Arizona, and Chihuahua. 



