MOUNT RAINIER The Forests of Mount Rainier National Park

MOUNTAIN HEMLOCK (TSUGA MERTENSIANA)

The mountain hemlock (figs. 18, 19, and 20) is found on the Pacific coast from the Sierras of California to the northern part of Alaska where it grows at sea level. On Mount Rainier it occurs at altitudes of from 3,500 to 7,500 feet. It forms dense forests under 4,500 feet, where it is often a fair-sized tree 50 to 90 feet high. With the ascent of the mountain it diminishes in height and the branches become gnarled and twisted. Near timber line the trunk is dwarfed and bent at the base and the crown becomes a flattened mass of branches lying close to the ground.

Fig. 18.—The feathery foliage of mountain hemlock (Tsuga mertensiana), Grand Park, Mount Rainier National Park. Photograph by A. H. Denman.

The mountain hemlock is abundant on high, rocky ridges, but the best stands are on cool, moist soil at the heads of ravines, on flats, and on gentle slopes with a northern exposure.

Fig. 19.—Two solitary mountain hemlocks (Tsuga mertensiana), Spray Park, Mount Rainier National Park. Photograph by Geo. O. Ceasar.

This tree seeds every year. In good seed years the upper branches are laden with a profusion of beautiful, deep-purple cones, often in such abundance as to bend down the branchlets with their weight. The reproduction is slow. In the high mountains the trees are buried in snow from October to late in June, and the growing season is very short.

Fig. 20.—A gnarled, wind-swept mountain hemlock (Tsuga mertensiana), near the upper limites of tree growth, Spray Park, Mount Rainier National Park. Photograph by A. H. Denman.