FAMILIES OF FLOWERING PLANTS 155 
by the perfect flowers, which bear glands alternating with the petals; 
stamens twice as many as the petals; fruit capsular, the carpels nearly 
distinct. The delicate flowers of Limnanthes Douglasii are sometimes 
seen in cultivation, but the family is of slight importance. 
Family Anacardiaceae. Cashew Family. The trees and shrubs 
comprising this family may nearly always be recognized by the milky, 
often caustic juice, inconspicuous flowers, and ovary containing a single 
ovule; the leaves, moreover, are without glands or dots. There are 
Fig. 134. The poison sumach (Rhus Vernix). After Britton & Brown, Ill. Fl. Northeast. U. s. 
about 50 genera and 400 species, most abundant in tropical regions. In 
our own area the family is represented by the sumachs (Rhus), some 
species of which are quite harmless and extremely ornamental, while 
others are highly poisonous. The poison oak (R. Vernix) or swamp 
sumach is the most virulent of these, while the common poison ivy (ZR. 
radicans) is dangerous to many people. The researches of specialists 
during the last few years have shown that the poisonous principle re- 
sides in a volatile oil which occurs in all parts of the plant; also that 
the best remedy is a solution of acetate of lead. 
In the tropics there are a number of important economic trees be- 
longing to this family. The fruits of Anacardium occidentale, known as 
cashew nuts, are edible after the acridity has been removed by roast- 
