POISON OAK AND SOAP PLANT 



By Stewart H. Burxham. 



/^LOSELY related to the poison ivy and poison sumac of 

 ^ the east and quite similar in its effects is the poison oak 

 (RJuis diversiloha) M California. La Yedra, as the ^Mexicans 

 called it, is either a low erect shrub or it may ascend trees bv 

 aerial roots to the height of 15 feet or more. The tiny green- 

 ish flowers appear with the leaves during the latter part of the 

 wet season in small axillary panicles, and later in the season 

 are succeeded by a whitish berry-like drupe. The variouslv 

 lobed or toothed (rarely entire) ovate leaflets, at the com- 

 mencement of the dry season, often turn to shades of brilliant 

 crimson and bronze, and the shrub becomes very attractive. It 

 cannot stand the winters of the high Sierras. It is confined to 

 the foothills and to the inner and outer Coast Ranges, where 

 it often forms thickets along the banks of streams and on cool 

 northern slopes. I seem to be a favored individual, when 

 brought into contact with plants of the sumac family, and only 

 once have I felt any of their virulent effects. One warm Feb- 

 ruarv day in 189 5. while descending thorugh a ravine in the 

 San ]\Iateo mountains west of Stanford University, along a 

 little path in the chaparral, I was obliged to brush through a 

 considerable thicket of poison oak. Although I tried carefully to 

 keep the bushes from touching my face, still for a few days 

 afterwards one or two little spots on my cheek showed that I 

 had been poisoned. 



Mary Elizabeth Parsons in her book, "The Wild Flowers 

 of California," speaking of the poison oak, says : "Horses eat 



