718 TEXTBOOK OF BOTANY 



Shreve, Forrest. The Cactus and Its Home. Williams & Wilkins Company. 

 1931. 



Small, J. K. Palms of the continental United States. Sci. Monthly. 32:240-255. 

 1931. 



Swingle, D. B. A Textbook of Systematic Botany. McGraw-Hill Book Com- 

 pany, Inc. 1934. 



U.S.D.A. Yearbook of Agriculture. 1937. 



Numerous manuals containing descriptions of both wild and cultivated plants 

 are available. 



