Bailey & Bailey: Woody Plants of National Parks 153 



long, the margins not toothed or finely toothed; flowers small, greenish-white, 

 borne in rounded or flat-topped clusters in the leaf-axils; fruits flat, roundish, 

 winged all around, about 1/3 to % inch in diameter, including the wing. 



As is characteristic of the orange family, the leaves are covered with small 

 transparent dots which may be seen when held up to the sunlight. The plants, 

 when bruised, have a strong odor resembling hops and the fruits have been 

 used in brewing as a substitute for hops.^"* 



Occurrence. — grand CANYON, 3,000 to 8,000 feet. North Rim: near Bright Angel 

 Point. South Rim: near Yaki Point. Canyon, common on both sides of the Colorado 

 River: Hermit trail, J/j mile below Santa Maria Springs; Bright Angel trail about ^ 

 mile below South Rim; Indian Gardens; Kaibab trail above Cottonwood Camp; near 

 Roaring Springs. 



Sumac Family (Anacardiaceae) 



Field Guide to the Genera 



Leaf-blades thinnish; flower clusters borne in axils of leaves, the slender stems 

 drooping; fruits whitish, globose, smooth, marked with dark green or black 

 veins TOXICODENDRON, p. 1 53. 



Leaf-blades thickish, or somewhat leathery; flower clusters terminal, stiffly erect; 



fruits red, hairy RHUS, p. 154. 



Poison Ivy, Poison Oak (Toxicodendron (Tourn.) Mill.) 



Poison oak and poison ivy are widely distributed in the United States, 

 poison oak in the far west and poison ivy east of the Great Western Divide. 

 Many botanists have considered them as belonging in the genus Rhus, but we 

 are following here the recommendation of the committee on horticultural 

 nomenclature-''^ in recognizing the separate genus. 



The name toxicodendron, is from the Greek meaning poison tree. The 

 word toxicon, Greek for bow (referring to the bow and arrow), has come to 

 mean poison because arrow poisons were among the first poisons used by man. 

 The plants contain an oil which, when it comes in contact with the skin, is 

 poisonous to many people, causing severe inflamation and swelling. Many 

 remedies have been recommended, including external applications of solutions 

 of ferric chloride, potassium permanganate, or baking soda, but none of these 

 do more than offer temporary relief after the rash has appeared. It sometimes 

 helps to apply a thin film of laundry soap or a strong solution of baking soda 

 to the hands and face before going into the field and then to wash thoroughly 

 with strong soap after returning home. If one is very susceptible to the 

 poison, clothes which have come in contact with the herbage should be imme- 

 diately laundered because they may hold the oil for some time and may even 

 affect persons who have not been outside. 



Poison oak and poison ivy are not common in the national parks because 

 they usually grow at elevations below that included in most of the park areas. 



34 McMinn, H. E., Illustrated Manual of California Shrubs, p. 260. 1939. 



35 American Joint Committee on Horticultural Nomenclature, Standardized Plant 

 Names. Second Edition. 1942. 



