PICEA EXCELSA AND RUBRA 115 
even after an endurance of the late severe May frost 
of 1915, and the unusually long visitation of cold 
late winter winds of 1916 and 1917. 
GROUP II 
P. Excersa, Rupra, Nicra, ALBA, ALBERTIANA 
Whilst towering firs in conic forms arise, 
And with a pointed spear divide the skies, 
M. Prior, 
The primary instinct of an uninstructed mind would 
in all probability regard the Common Spruce (P. 
Excelsa) as the representative type of what all 
properly conducted Spruces should ‘and ought to be. 
Possibly, if his inclinations carried him a little 
farther on the paths of investigation, he would notice 
that the leaves of some of these similarities were a 
little longer than others, and also that perhaps a 
different hue of colour here and there was apparent, 
and one or two little minor differences of this sort. 
But, on the whole, he would concur that the majority 
of Spruces, although labelled by the doctrinaires with 
different names, partook of a sufficient resemblance 
to the Common Spruce to justify him in including 
them mentally in one self-same category. If he went 
a little farther still upon his journey of investigations, 
the chances are he would soon be induced to modify 
his opinions. 
Let us suppose that he came across a Picea Rubra, 
he would at once notice a certain resemblance that 
‘it bore to the Common Spruce. He would perceive 
that the leaves of the P. Rubra were, on the whole, 
shorter than those of the P. Excelsa. While the 
Picea Rubra’s leaves reach about half an inch in 
length, those of the Excelsa average about twice 
the length. Yet a young and weakly Common 
Spruce can often be found with leaves as short. The 
colour, too, is the same, we might almost say precisely 
the same. So far we have not got much forwarder, 
9 
