VOLUME LX NUMBER 3 
Ek 
BOTANICAL: CeAZETTE 
SEPTEMBER 1915 
IS THE BOX ELDER A MAPLE? 
A STUDY OF THE COMPARATIVE ANATOMY OF NEGUNDO 
Amon B. PLOWMAN 
(WITH PLATES V-X) 
The difficulties and uncertainties of classification, upon the 
basis of purely superficial characters, is perhaps nowhere better 
exemplified than in the case of the common box elder. 
This tree occurs in large numbers over the greater part of its 
range throughout the northern, portion of the United States and 
Canada, and only less frequently in the Southwest and along the 
Pacific Coast. It is also very generally cultivated in Europe. 
With its diffuse, irregular mode of branching, and its light 
green, compound leaves, the box elder is one of our most easily 
identified trees, yet it possesses combinations of characteristics that 
constitute a troublesome puzzle to the systematist. 
The tree habit is manifestly quite different from that of the true 
maples; the leaves are wholly unlike maple leaves; the sap is similar 
to that of maples, but the odor of the young twigs is unlike any- 
thing ever produced by a maple; the fruit is quite like the maple 
fruit; yet, unlike the maple, the box elder is anemophilous and 
strictly dioecious; the: wood is maple-like in appearance and 
structure, though much softer, lighter, and less durable. 
These and many other peculiarities of the box elder have engaged 
the attention of botanists since LinNAEUS named this tree Acer 
Negundo in 1753. To the mind of LiynaEvs, even approximate 
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