ENGELMANN—OAKS OF THE UNITED STATES. 
[375 
exgelmann o 
the Black-oaks is brittle and porous, makes poorer firewoodland, 
made into barrels, holds only dry substances. Undoubtedly the 
microscopical investigation of both classes of oak-wood will sci¬ 
entifically establish and confirm these distinctions. 
While many other trees, such, as Pines, Walnuts, Hickories, 
Gleditschia, etc., grow rapidly in the first decades of their life, 
and make narrower and narrower annual rings as they grow old¬ 
er, the oaks either hold their own, the annual rings being as wide 
in age as they are in youth, or they grow more rapidly after the 
first 50 or 100, or even 156 years of their existence. 9 
The winter-buds, especially the terminal ones, show some cha¬ 
racteristic differences ; they are larger or smaller, acute or obtuse, 
smoothish or hairy or tomentose; \uercus Garryana can be 
readily distinguished from all the allied Californian oaks by its 
large, pointed, tomentose winter-buds. 
In the leaves, so extremely variable in form, certain types are 
generally recognized. It is not here the place to expatiate on 
these well-known topics ; but I may be allowed the observation, 
that those oaks, which in the perfect state have deeply-lobed or 
pinnatifid leaves, show in young shoots or on adventitious branch- 
lets less divided or only dentate, sinuate, or even entire Ifaves 
(e.g. J^. alba , steliata , fat cat a , coccinea, palustris, etc.), while, 
singularly enough, the oaks whose leaves in the adult tree are 
entire or nearly so, often have on the young shoots dentate or 
lobed leaves. I need for examples only refer to aquatica , Jj. 
Phellos , and virens; and even nigra belongs here.f|H 
The vernation of the oak leaves has sometimes been mentioned 
as conduplicate, meaning that the upper sides of both halves of the 
nascent leaf are applied together, and this really is the case with 
most oaks which I have been able to examine in this early stage. 
We find it both in White and Black-oaks—almost always, I be¬ 
lieve, in those with broad and deeply-lobed leaves; I mention 
only J^. alba , macrocarpa and Garryana , Jg. coccinea and pa- 
lustris, and also the forms allied to Jg. Prinus , even those with 
narrower, dentate leaves. In the more deeply-lobed, broad-leaveH 
Black-oaks the two halves of the leaf are, besides, plicate parallel 
with the principal nerves. H 
Next to these range the oaks with the young leaves concave 
and imbricately covering one another. Such we find in Q. stel- 
Hftofthe first, and 1 
HL tomentose, thick,; 
| , las have broader and 
,resimbricatively cover 
are convex on the upp 
i, Such is the case 
‘glica, chrysolepis , an 
|, Wislizeni; I find I 
ML|./a/az/a. 
le narrow-leaved oaks 
its, the halves being sj 
so that only the 1 
atof the young leaf is s< 
as a squarrose appear 
nation it is compact. 
Phellos , heteroph 
• wean inflexed vern 
fiascent leaf being cun 
Neve that the chara 
;, allied species o 
Hovelling the intricate 
young leaves of air 
/' .tie down, which in so 
lllps, or it disappears 1; 
dilate one-celled hi 
I % of the young le 
W»stellately connecter 
, sometimes branch 
& *• I notice these arti 
I * /a - and less cons 
®“lack-oaks, in a. , 
: f*. and laurifolia 
K Scales ” are no sc 
iWowhair, and the 
m- 
W Nation and me 
represent charac 
f ,' 1Sll y confounded Cn 
T 1 ® readily be distin 
