Botany and Zoology. 153 
IlL Borany AND ZOOLOGY. 
ing results of the long and close scrutiny which Dr. Engelmann 
has given to this vexed genus of trees. The paper begins with 
, var, Uthensis, DeC.), Q. Gunnisoni, Q. undulata, 
described by Torrey long ago from this district, Q. pungens of 
Liebman, in part, Q. oblongifolia, @. grisea, an Drum- 
mondii of Liebman,—‘ in herbarium specimens all distinct enough, 
but, looking around us, the very abundance of material must 
shake our confidence in our discrimination [since] within the com- 
pass of a few hundred yards we find not only the forms above 
unite them all as f one single, polymorphous species 
one oak behaves thus, why not oth Thrown upon a sea of 
r. Engelmann reviews the principal characters, one by one, to 
settle their relative value; and, in doing so, brings out the main ~ 
,» as ize attained, while it gives character to 
eastern species (only the southern live oak occurring both as lar 
tree and shrub, an ually fruitful in both forms), fails on the 
between ‘white oaks’ and ‘black oaks’ is based on correct ob- 
servation. The paler, ashy-gray bark of the former, and the darker 
) 
Am 
i ar 
Sealy or flaky, that of the black oaks is usually rou, her and deeply 
cracked or furrowed.” “ Moreover, the wood of the white oaks is 
“ d of m g narrower and nar- 
rower rings as they grow older, the oaks either hold their own, 
the annual rings being as wide in age as in youth, or they grow 
i Tapidly after the first 50, 100, or even 150 years of their ex- 
ce, 
