Next to the Douglas fir the western hemlock is the most abundant tree in
the forests of Oregon and Washington. It occurs from Alaska southward to
northern California. About Mount Rainier it is found up to an altitude
of 5,000 feet. In the river valleys in moist situations it is a large
tree, sometimes reaching a height of 250 feet and a diameter of 5 feet.
On the high ridges it is stunted. It grows best on moist deep soils in
dense forests, but thrives under almost all conditions of soil and
exposure if provided with plenty of moisture.
Western hemlock (figs. 6 and 7) is usually associated with Douglas fir
and red cedar, but sometimes forms a forest of nearly pure growth. The
hemlock produces abundant seed each year, although it is more prolific
at irregular intervals. The seeds germinate readily on decayed moss and
rotten wood as well as upon the mineral soil. Seedlings frequently grow
on fallen logs and extend their vigorous roots around the side until
they reach the ground and become firmly anchored in it. Young hemlocks
thrive in the shade. On logged-off areas which have not been burned over
and which are partially shaded by uncut trees, the reproduction of
hemlock springs up, to the exclusion of the more valuable Douglas fir.
[Illustration: FIG. 6.--The lower slope forest, near Longmire Springs,
altitude 3,000 feet, here composed largely of western hemlock (_Tsuga
heterophylla_); the tree on the extreme left is a Douglas fir
(_Pseudotsuga taxifolia_).