﻿168 Canadian Bccord of Science. 



Caiidolle's rrodroinus, Vol. xvi., second section, pp. 413-14, 

 published in June, 1868, recognizes our Canadian species 

 as three : nigra, the black spruce or double spruce of 

 Anoio-Americans ; riihra, with leaf-faces albo-glaucescent 

 (indicating that he probably had a form of nigra in view) ; 

 and alha, with o\'al-oblong, or oval-cylindrical cones, 

 pendulous, on longer branchlets than the others (the 

 geographical range extending to the Eocky Mountains, on 

 authority of specimen from Bourgeau). 



In Dr. Eobert Bell's chart of the northern limits of 

 trees forming the Canadian forests, the two spruces, alha 

 and nigra, are lined together. 



Prof. Macoun, in the Catalogue of Canadian Plants 

 of the Geological Survey of Canada, gives two species, 

 combining rubra with nigra. 



Sir Joseph Hooker, in his tabulation in the Outlines of 

 Distribution of Arctic Plants (Linnsean Transactions, 

 1864), gives only alha and nigra, and Sereno Watson, 

 in the Botany of California, also dismisses our spruces 

 in N.E. as " two species." 



The following descriptions of the several species are not 

 thrown into systematic form, lieing merely intended to 

 call attention to points of difference, and to suggest 

 observation and enquiry, so that the necessary information 

 may be obtained for the formation of accurate and per- 

 manent diagnostic characters : 



1. PiCEA ALBA. — Link, in LinnjT'a, xv., p. 519. 



Picea alha, the white spruce of Canada, is recognized at 

 a distance, from the allied species, by the comparative 

 massiveness of the foliage with which its horizontal or 

 pendant boughs are clothed, and by its glaucous or 

 whitish-green tint — the leaves when newly expanded 

 being pale and silvery, as if covered w^ith the most 

 delicate coating of hoar frost. This appearance, however. 



