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Trees of Yosemite (1932, 1948) by Mary Curry Tresidder

[Pine Family]

Mountain Hemlock

Tsuga mertensiana Sarg.

Mountain Hemlock Cones Slightly Less Than Natural Size

Mountain Hemlock Tree

The Japanese name of the hemlock is Tsuga; it is a favorite in Japanese landscape gardening. (The hemlock of Socrates’ fatal potion was obtained not from a tree of this family but from an herb related to our wild carrot.) “Graceful” is the adjective which nearly every writer applies to this tree. Tall and slender, with drooping branches and tapering crown, the Mountain Hemlock is one of the trees whose charm is increased by its association with high-mountain memories.

Its range is from 8,000 feet upward, usually in fairly moist places. It is therefore not native on the floor of Yosemite Valley, but a few small trees which have been planted there are thriving. One benefit of the blight which has been so destructive in the forests of Lodgepole Pine is the attendant increase in hemlocks. Seedlings do not thrive in too close a forest, and with the opening of these places to sunlight the young Mountain Hemlocks have seized their opportunity.

Under most favorable conditions, this hemlock may leach a height of one hundred feet; near timber line it, like the Juniper and the White-Bark Pine, may be found gnarled, weather-beaten, flattened down. Normally, however, the resilient hemlock sapling bows beneath the snow during the winter, only to turn upward again when released.

Hemlock bark is rich in tannin. That of the young trees is silvery, but it soon becomes roughened and finally much ridged and furrowed. It tends to be a dark reddish-brown, often with a purple tinge that echoes the purple coloring of the pendulous cones. The latter vary strikingly, however, on different trees. The cones ripen in a single season; they shed their seeds in September or October, and fall during the winter months. They are from half an inch to three inches long.

The needles are bluish-green, blunt-pointed, growing in spirals around the branchlets but appearing thicker on the upper side because of the twisting of their slight stems. They persist for about four seasons.

The Mountain Hemlock is associated with the Lodgepole Pine in flat, moist canyons, as along the Tioga Road between Tenaya Lake and Fairview Dome; with Red Fir and Western White Pine on high slopes of northerly exposure, such as it finds along the Forsyth Pass Trail above Lake Tenaya, or along the southeasterly wall of Matterhorn Canyon; and with White-Bark Pine near the ridges of the Hemlock’s upper limits, far up on the Lyell Fork of the Merced, or at Young Lakes below Mount Conness.

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