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of tree is the yellow pine, Pinus ponderosa. The individual trees usually 
stand well apart, and there is plenty of sunshine between them. The 
vegetation consists of a rather poor quality of bunch grass and other 
scattered herbaceous plants, and a very scattered undergrowth, made 
up chiefly of chamise (Hunzia tridentata). In their upper elevations 
the yellow-pine forests are denser, and often contain a considerable 
amount of Douglas spruce (Pseudotsuga mucronata) and California 
white fir (now treated as a form of Abies concolor), with an undergrowth 
of snow brush (Ceanothus velutinus), manzanita (Arctostaphylos patula), 
and chinquapin (Castanopsis chrysophylla minor). 
The lodgepole pine forests also lie chiefly on the eastern slope of the 
mountain, at a higher elevation than the yellow-pine forests, and present 
avery different character. The trees are small, thin-barked, and very 
easily killed by fire. The underbrush, made up chiefly of a creeping 
manzanita (Arctostaphylos nevadensis) and the waxy currant (Ribes 
cereum), 18 never dense, and often is entirely wanting over large areas: 
Grass is sparse and not of the best quality. The best grazing plants 
are lupines. In the lodgepole pine forests the trees are usually set © 
close together, so close, indeed, that it is often difficult to ride through 
them on horseback. At a still higher elevation than the lodgepole 
pine, extending, indeed, almost to timber line, is the belt of black hem- 
lock (Tsuga pattonit), a usually open forest with underbrush of two 
huckleberries ( Vacciniwm scopariwm and V.membranaceum) or, especi- 
ally at high elevations, wholly devoid of underbrush. Almost no graz- 
ing is carried on in this hemlock belt, though the bands of sheep often 
traverse it on their way across the mountain crests to the west slope. 
The heavy west slope forests are deep, dark, and dense, and consist 
chiefly of a mixture of the Douglas spruce (Pseudotsuga mucronata) 
and the white fir (Abies grandis), with often considerable quantities 
of other trees. These forests bear a usually dense undergrowth and 
exceed in humidity both of the forests mentioned above. The grazing 
in the west slope forests consists chiefly of weeds and browse, the latter 
made up largely of vine maple (Acer circinatum). 
The “burns” that occur in the Cascades depend largely upon the 
character of the forests in which they lie. For sheep-grazing purposes 
burns in the yellow-pine forests are of small importance one way or the 
other, as very little permanent change in the herbage is effected by 
them. The scant grass and underbrush do not make a destructive 
tire, while the bark of the yellow pines is so thick and so nearly devoid 
of resin that only under exceptional circumstances is a mature tree 
killed. The saplings, however, up to an age of fifteen or twenty years 
are readily killed by fire, and frequently an old tree well supplied with 
resin, exuding about some injury near the base, takes fire there year 
after year, gradually burning deeper and deeper, until the tree is 
destroyed. The scars thus made are commonly known as ‘fire cracks.” 
On rocky slopes in the higher elevations of the yellow pine forests, 
- where there is a large admixture of white fir and Douglas spruce, and 
