Mar., 1921] 
MCNAIR A STUDY OF RHUS DIVERSILOBA 
The sterile and fertile flowers of this species (which is very near R. Toxicodendron) 
present some notable differences. The sterile, which is figured by Hooker, has rather deeply 
lobed leaflets, sometimes in fives and larger flowers; in the fertile the leaflets are almost 
entire or slightly lobed and the flowers considerably smaller, so that it might readily be 
taken for a distinct species. The fruit is white, somewhat pubescent and gibbous. 
Torrey and Gray (58) summed up the previous knowledge of the 
plant and renamed it Rhtts diversiloba, the name by which it is now more 
commonly known. 
The difference between R. diversiloba and R. Toxicodendron is so small 
that their proper classification forms a bone of contention between botanists. 
Those botanists who believe in innumerable species are in favor of their 
separation, w^hile the more conservative are opposed to it. Greene (21) 
considers R. .diversiloba ''a peculiar type of Toxicodendron belonging ex- 
clusively to the Pacific Coast." Engler (15) believes diversiloba a sub- 
species oi Toxicodendron. The only botanical ground for the separation of 
the two into different species is a slight difference in the shape of their leaflets 
(Gray, 17). A three years' study of Rhus diversiloba and a recent study of 
R. Toxicodendron in Pennsylvania and Maryland for a year have enabled 
me to make a personal comparison of the two plants. The tracings of the 
outlines of mature leaves of both plants (figs, i, 2) and a tabular account 
Fig. I. Tracings of mature leaves of Rhus Toxicodendron (Reduced 6%X). 
