NOTE. 
Tue first volume of this work was issued in October, 1890. At that time it was believed that 
the forests of North America, exclusive of Mexico, contained only 422 species of trees and that these 
could be described in twelve volumes illustrated by 600 plates. 
The interest in trees and dendrological study have greatly increased in the United States since the 
first volumes of this Silva appeared; and recent researches have disclosed the presence on this continent 
of a number of arborescent species whose existence was not even suspected ten years ago, and have 
added much to the knowledge of the geographical distribution of North American trees. Most of 
these additions to our silva are new to science; others were formerly considered shrubs but are now 
known to be often arborescent in habit, and others regarded as varieties in earlier volumes are now 
believed to be best treated as species. Two supplementary volumes are needed for the description and 
illustration of these additions, and the completed work contains the descriptions of 585 trees, of several 
varieties of trees and of a number of shrubs, and 740 plates. 
C. S. SARGENT. 
ARNOLD ARBORETUM, 
June, 1902. 
