PIPER—FLORA OF THE STATE OF WASHINGTON. 4] 
the red fir (Pseudotsuga mucronata) which in the Puget Sound region 
often makes up over 90 per cent of the forest over large areas (PI. 
VIT), and up to an altitude of 1,000 meters seldom forms a smaller 
element of the total forest than 60 per cent. Nearly all of western 
Washington below the altitude mentioned possesses this character- 
istic red fir type of vegetation, except a narrow strip along the 
Pacific Ocean. Here the Sitka spruce (Picea sitchensis) becomes 
the dominant tree, making up from 25 to 75 per cent of the forest, 
while the red fir falls to 10 per cent or less. This narrow strip has 
heen considered as belonging to the next higher zone, the Canadian, 
but for reasons hereafter expressed we would include it in the Humid 
Transition. 
The principal features of the vegetation of western Washington 
may be discussed under the three heads of the principal types of soils, 
namely, the Uplands, the Bottom Lands, and the Gravelly Prairies. 
Plant associations of lesser importance, but of marked character, are 
those of the seashores and of sphagnum bogs. 
UPLANDS. 
The vegetation of the uplands throughout the Pacific area in 
Washington is a plant association in which the red fir predominates. 
The size of this tree and the luxuriance of the associated plants 
varies with the character of the soil, but otherwise the formation 1s 
remarkably uniform. In forests in dry or sterile soils the commonest 
undershrubs are salal (Gaultheria shallon) and Oregon grape (Ber- 
beris nervosa), while the bracken fern (Pteridium)is the most con- 
spicuous herb. Shrubs or trees of Scouler willow (Salix scouleriana) 
are also constantly associated. 
In better soils the same shrubs remain, but the salal especially 
becomes much more luxuriant, often forming almost impenetrable 
thickets. When, however, the red fir is at its best, forming dense 
forests into which the sun searcely penetrates (Pl. VIIL) the salal 
and Oregon grape are usually much less conspicuous. Under such 
circumstances the ground is covered with a thick layer of mosses and 
scattered crowns of Chamisso’s shield fern (Polystichum munitum). 
Among the few shrubs which thrive in such dense shade is the red 
huckleberry (Vaccinium porvifolium). Following the destruction 
of a red fir forest by logging and subsequent burning, as has been too 
commonly the case, there is a marked sequence in the plants that 
appear, usually as follows: The first are nearly always the fireweed 
(Epilobium spicatum) and the bracken (Pteridium). These are 
closely followed by the dewberry (2ubus macropetalus) which the 
following year fruits heavily and then gradually disappears. The 
thimbleberry (Rubus parviflorus) is often abundant also, as is red- 
