218 MEDICINAL AND POISONOUS PLANTS, 
is to rub thoroughly the affected part every few hours with 
a concentrated solution of sugar of lead in alcohol of 50-75% 
strength. As alkalis convert the oil into a harmless soap, 
F 1g. 210.—Poison-ivy (Rhus Toxicodendron, Sumac Family, Anacardiacee). 
a, spray showing air-roots and leaves, 3; 6, fruit, 4. (Chesnut.)— 
Climbing or trailing shrub becoming 6-15 m. long, sometimes erect 
and bushy; leaves smooth or downy; flowers green; fruit smooth, waxy, 
grayish. Native home, North America. 
relief is also found by the application of a strong solution of 
cooking soda, as soon as possible after the poisoning. 
A fixed oil similar to cardol has been found to be the cause 
of poisoning by two of our native orchids known as lady- 
