APPENDIX. 225 



Willows. 

 Poplars. 



Plantanus, Elms, Sycamore, for various purposes of shade, 

 shelter, and wind-breaks. 



Evergreens. 



American White Spruce deserves far more attention than 

 thus far enjoyed. It is the most lasting of all spruces. 



Norway Spruce. 



Scotch and Austrian Pine are valuable for close planta- 

 tions for shelter. They are, however, deficient as to longevity, 

 losing their vigor much sooner than the native American 

 species. 



European Larch is suited to the northern parts of 

 Missouri, Iowa, and farther north. 



UNIVERSITY OP PENNSYLVANIA, 

 PHILADELPHIA, PA., February 27, 1892. \ 



PROF. EDWIN J. HOUSTON, 



1809 Spring Garden Street, Philadelphia, Pa. 

 MY DEAR PROFESSOR, I am in receipt of your favor of 



the 20th inst., and I take pleasure in sending you a list of 



trees suitable for planting in the Southwestern States and 



California. 



JBetula occidentalis, Hook. Black Birch. For ornamental pur- 

 poses, grows ten to twenty feet high. 



Quercus undulata, Torr. Oak. Four varieties, valuable for 

 timber and for masting, furnishing, as they do, an abun- 

 dance of sweet, edible acorns. 



Salix cor data, Muhl., var. vestita, Anders, Diamond Willow, 

 abundant in Yellowstone regions, valuable for furnishing 

 unique canes. 

 P 



