number of species native in the United States is very small. 



Additional references for genera and families of trees are cited in the 

 Forest Service Check List (Little 1953 B). Some later titles will be 

 included in the forthcoming revision. 



See also: Bailey, L. H. 1933 E; Benson, Lyman 1969 Ariz.; Benson, 

 Lyman 1969 Calif.; Turner, B. L. 1959 Tex. 



Argus, George W. 



1973. The genus Salix in Alaska and the Yukon. Can. Natl. Mus. Nat. 

 Sci. Publ. Bot. 2, 279 p., illus. (maps). Ottawa, Can. 

 Bailey, L. H. 



1944. Revision of the palmettoes. Gentes Herbarum 6: 367-459, illus. 

 [Sabal, Serenoa. ] 



Bailey, Virginia Long. 



1962. Revision of the genus Ptelea (Rutaceae). Brittonia 14: 1-45 

 (maps). 



Barkley, Fred Alexander. 



1937. A monographic study of Rhus and its immediate allies in North 



and Central America, including the West Indies. Ann. Mo. Bot. 



Gard. 24: 265-498, illus. (maps). 

 Bomhard, Miriam L. 



1963. Palm trees in the United States. Slightly rev. U.S. Dep. Agric, 

 Agric. Inform. Bull. 22, 28 p., illus. (First printed 1950.) 



Britton, N. L., and J. N. Rose. 



1963. The Cactaceae: descriptions and illustrations of plants of the 



cactus family. 4 v. bound as 2, illus. Dover Publications, New York. 



(Reprint of Carnegie Institution of Washington Publ. 248, 4 vol., 



illus. (part col.). 1919-1923; 2d. ed. 1937.) 

 Cronquist, Arthur. 



1945. Studies in the Sapotaceae, III. Dipholis and Bumelia. J. Arnold 

 Arbor. 26: 435-471. 



Cutler, Hugh C. 



1939. Monograph of the North American species of the genus 

 Ephedra. Ann. Mo. Bot. Gard. 26: 373-428, illus. 

 Dallimore, W., and A. Bruce Jackson. 



1967. A handbook of Coniferae and Ginkgoaceae. 4th ed. revised by S. 

 G. Harrison, with drawings by Miss G. Lister and H. R. W. Herbert. 

 729 p., illus. St. Martin's Press, New York. (Reprint of 1966 ed.) 

 Dawson, E. Yale. 



1963. How to know the cacti: pictured keys for determining the native 

 cacti of the United States and many of the introduced species. 158 p. , 

 illus. Wm. C. Brown Co., Dubuque, Iowa (Pictured Key Nature 

 Series.) 

 Dugle, Janet R. 



1966. A taxonomic study of western Canadian species in the genus 

 Betula. Can. J. Bot. 44: 929-1,007, illus. (maps). 



