Hayes, Doris W., and George A. Garrison. 



1960. Key to important woody plants of eastern Oregon and Washing- 

 ton. U.S. Dep. Agric, Agric. Handb. 148, 227 p., illus. 



Randall, Warren R. 



1961. Manual of Oregon trees and shrubs. 234 p., illus. Oreg. State 

 Coll. Coop. Assoc, Corvallis. (Reprinted 1975, Oreg. State Univ. 

 Bookstores.) 



Ross, Charles R. 



1972. Trees to know in Oregon. Artist Hugh Hayes. Oreg. State Univ. 

 Coop. Ext. Serv. Bull. 697 rev., 96 p., illus. Reprinted. Corvallis. In 

 cooperation with Oreg. State For. Dep., Salem. 



Yocum, Charles F. 



1964. Shrubs of Crater Lake National Park. 82 p., illus. Crater Lake 

 Nat. Hist. Assoc. Published in cooperation with the National Park 

 Service. 



Pennsylvania 



See also: Grimm, William Carey 1957 G. 

 Grimm, William Carey. 



1950. The trees of Pennsylvania. 363 p., illus. Stackpole and Heck, 

 New York, Harrisburg. (Superseded by Grimm 1962 G.) 

 Ibberson, J. E., A. B. Mickalitis, J. E. Aughanbaugh, and C. L. Morris. 

 1971. Common trees of Pennsylvania. 55 p., illus. Dep. Environmental 

 Resources, Harrisburg. 

 Illick, Joseph S. 



1925. Pennsylvania trees. Ed. 5. Pa. Dep. Forests and Waters Bull. 11, 

 237 p., illus. Reprinted 1928. (Out of print.) 

 Li, Hui-lin. 



1973. Trees of Pennsylvania, the Atlantic states and the Lake states. 

 276 p., illus. Univ. Pa. Press, Philadelphia. 



Puerto Rico 



See also: Virgin Islands. 

 Duke, James A. 



1965. Keys to the identification of seedlings of some prominent woody 

 species in eight forest types in Puerto Rico. Ann. Mo. Bot. Gard. 52: 

 314-350, illus. Reprinted in Odum, Howard T., and Robert F. Pi- 

 geon, eds. 1970. A tropical rain forest: a study of irradiation and 

 ecology at El Verde, Puerto Rico. P. B-239-274, illus. U.S. Atomic 

 Energy Comm., Washington, D.C. 



Hargreaves, Bob, and Dorothy Hargreaves. 



1965. Tropical trees found in the Caribbean, South America, Central 



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