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A TRICARPELLARY WALNUT* 
Bv WirLLIAM Н. LAMB 
A tricarpellary walnut is one that is separable into three 
divisions. In general walnuts are bicarpellary, but tricarpellary 
forms do occur, especially in our so-called "English walnut," 
Juglans regia L. The accompanying sketch shows an end view 
and diagrammatic cross section of one of these interesting forms. 
The term "English walnut," by the way, is a misnomer, for 
Juglans regia is not a native of England at all. It is extensively 
cultivated in England and on the continent, but is native to 
southeastern Europe, Greece, Asia Minor, and China. It has 
been more properly called “Persian walnut." 
Fic. 1. End view, natural size, and diagrammatic cross section of a tricarpellary 
walnut (Juglans regia L.). 
Before discussing the significance of a tricarpellary walnut, it 
might be well to consider just what a walnut is. A walnut is 
not a fruit. Indeed it is an interesting fact that no species of 
Juglans bears edible fruit. The fruit proper is a bitter, green or 
black, more or less fleshy drupe. It contains the walnut, just 
as a peach contains a large seed. If we were to throw away the 
fleshy part of the peach and retain the stone as a delicacy, we 
would be doing precisely what is done in the case of the walnut. 
The edible portions of a walnut are the large cotyledons. 
These cotyledons are deeply lobed in consequence of an in- 
* Published by permission of the Secretary of Agriculture. See also Torreya 8: 
136. 1908.—Ер. 
