20 MISC. PUBLICATION 101, U. S. DEPT. OF AGRICULTURE 
leaved bush, 1 to 10 feet high, found on both dry ridges and moist .| 
slopes up to about 5,200 feet in California and Oregon. It is a 
small-leaved and entire-leaved shrub variety of tanoak or tanbark 
oak (Lithocarpus densiflora, syns. Quercus densifiora, and Pasania 
densiflora) and is avoided by livestock unless better feed is wanting, — 
meriting mention here only because of local abundance. 
OAKS (QUERCUS SPP.) 
The oaks are a large group of woody, acorn-bearing plants almost 
exclusively confined to the Northern Hemisphere. About 75 species 
occur in the United States. In the eastern States the oaks are 
exceedingly important timber trees and have little or no economic — 
significance as forage save for a few species and in restricted local- 
ities. In the West oaks are well represented but, with relatively 
few exceptions, have only slight or negligible importance in the 
lumber trade, the use of the wood being mainly restricted to cord- 
wood, fence posts, mine props, etc. On the other hand, some of 
these oaks have greatest value as browse or in erosion prevention. 
The larger oaks of the Southwest and of the drier regions elsewhere 
are of great value as shade for range animals. Many species of oaks 
in this region are shrubs, often occurring as low bushes forming 
thickets or shinneries of wide extent. 
The most common classification of oaks is into two main groups: 
(1) White oaks, with prickleless smooth-edged leaves, annual acorns 
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(maturing the first season), and characteristically light-colored — 
bark; and (2) red (or black) oaks, usually with more persistent 
leaves whose veins frequently end beyond the margin in bristlelike 
or pricklelike awns or teeth, biennial acorns (maturing the second 
year), and often dark-colored bark. Other popular oak groupings 
include live oaks, with thick evergreen leaves; chestnut oaks, with 
more or less chestnutlike leaves; and dwarf scrubby shinnery oaks. 
As a matter of fact all these groups are somewhat artificial and 
tend to intergrade more or less. Probably the best classification of 
oaks is that of Trelease (135), who recognizes six subgenera or | 
sections, three of them occurring in North America, viz: 
(1) Leucobalanus, or white oaks. Very large to moderate-sized or smali | 
trees or sometimes shrubby; bark gray, mostly rough; wood close, hard, and 
whitish, with numerous tyloses; leaves never aristate (awn-margined); sta- 
mens rather numerous (about 7-9), the anthers short and blunt; styles short — 
and broad; fruit always annual (maturing first season), often long stalked, 
the scales mostly acuminate (tapered), often thickened and woolly, the acorn 
shell nearly glabrous not tomentose (woolly) within, the abortive ovules 
basal or subbasal. 
(2) Protobalanus, or intermediate oaks. A small group of five species. | 
Shrubs or small trees; bark gray-brown, scaly; wood close, hard, mostly brown- 
ish, with relatively few tyloses; leaves firm, entire or pungently toothed, — 
om 
mostly small; stamens numerous (8-10), the anthers pointed and rather 
long; styles short and broad; fruit biennial (maturing the second season), 
short stalked, the scales pointed, thickish and usually very woolly, the acorn 
shell tomentose (woolly) within, the abortive ovules lateral. 
(3) Erythrobalanus, or red oaks. Trees or shrubs; bark dark, not scaly; 
wood moderately hard, often reddish, more porous and with fewer tyloses 
than the white oaks; leaves often incisely lobed, the lobes or vein tips usually 
produced into awns or bristles; stamens rather few (4 or 5), the anthers 
mucro-pointed; styles elongated and spatula-shaped; fruits usually biennial 
but in some species annual, mostly subsessile (practically stalkless), the 
