2o6 Choice of Plant Material 



dry soil, and its rate of growth uiil be in proportion to its 

 feeding. Even the tolerance of shade is relative to the sup- 

 ply of water. And as vigorous constitution fights off dis- 

 ease, so, insect pests and fungus diseases attack the least 

 vigorous, and hence in the last analysis are to some extent 

 in relation to soil conditions. 



From what has been said, it stands to reason that all 

 descriptions of form and statement of characteristics, unless 

 more extended than can be given in this book, refer only to 

 some stage of development and to typical trees and condi- 

 tions, from which nature may deviate a hundred times. 



LIST OF TREES DESIRABLE FOR SHADE AND 

 ORNAMENT 



While in office at Washington, the writer spent much of 

 his leisure in becoming acquainted with the wealth of orna- 

 mental material planted in the small parks of the city (some 

 four hundred species). He caused to be compiled plats of 

 all the parks and small places, locating each tree by number, 

 so that at a glance, by reference to a numbered list, it could 

 be named. There was also compiled, under his direction and 

 personal supervision, a description of the species with such 

 notes of interest as the tree-lover and tree-planter would 

 appreciate. The manuscript, nearly completed ten years 

 ago, when the writer left office, has unfortunately remained 

 locked up in the drawers of the Department witli which 

 he had been connected, and failed so far of publication. 

 The writer mentions this incident merely to justify his pre- 

 suming to give advice on the choice of ornamental trees. 



The following list of nearly four hundred species and vari- 

 eties does not in any sense pretend to be a complete enumera- 

 tion of the trees which deserve attention, but it contains all 



