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The Cone-bearing Trees of Yosemite (1939) by James E. Cole


MOUNTAIN HEMLOCK

Tsuga mertensiana (Bong.) Sargent

Mountain Hemlock, Tsuga mertensiana
[click to enlarge]
Another inhabitant of high places in the park is the Mountain Hemlock which was held by John Muir to be “the most singularly beautiful of all the California coniferae ” Beautiful, because of lightness of form, it seems perfection in these high places where nature commands stern tools to fashion her favorites. The elegance of this graceful tree mountaineer is ever refreshing in contrast to the rugged staunchness of her more defiant associate trees; the Western White Pine, the Lodgepole Pine, the Western Juniper and the White-bark Pine.

The narrow, columnar crowns, often twenty or more feet in height and less than a yard in width, have fragile tops that droop daintily. Frequently a few conspicuous upper branches push out Sugar Pine-like beyond the others. When standing alone and even to a noticeable extent on forest grown trees, the trunks are commonly clothed with branches clear to the ground. Another distinctive trait of mature Mountain Hemlock is the habit of encircling themselves with a group of younger trees. These occasionally grow so thick and with the branches so intertwined that it is impossible to approach the parent tree without walking upon the mat of foliage. Much can be written about the alluring beauty of the Mountain Hemlock, but quite in vain, for as John Muir has said, “the best words only hint of its charms. Come to the mountains and see.”

Normally the Mountain Hemlock prefers northern exposures, around 9000 feet or more where snow banks linger. In these haunts it is so characteristic that its identification is possible even from a considerable distance. The drooping tops are singular to this species as well as the habit of retaining the lowermost branches. Examination of the foliage shows that the needles are singly attached to the branches somewhat similar to those of the Red Fir with which it may be associated. They differ in having a distinct and conspicuous petiole and in clothing the branchlets entirely although appearing thicker on the upper sides. The rounded needles are from one-half to three-fourths inch long and thickly clothe the short lateral branchlets. In the summer the dark green older foliage is mottled by the pale, blue-green growth of new leaves.

The trunks of hemlocks, as well as those of other trees growing on steep hillsides, are habitually bent at their bases. The older trees appear never to recover completely from the down-hill bending by heavy winter snows when they were saplings. From a distance the trunks of Mountain Hemlocks have a bluish-gray shade that changes to dark reddish-brown when the narrowly and deeply fissured bark is more closely examined.

The cones are found throughout the upper half of the crown. They are most abundant near the top where they hang in dense clusters at the ends of the slender twigs bending them down with their weight. Young cones seen by summer visitors are bluish-purple. They mature in the fall and are commonly about two inches long and one inch wide. The light brown scales of the mature cones stand rigidly at right angles to the cone axis. Empty cones may remain on the trees for a year while the new crop is developing and, together with the tassels of bluish staminate catkins and young cones, add even more decorations to these richly ornamented trees.

The Yosemite visitor who travels the Tioga Road will find Mountain Hemlocks growing with Lodgepole Pines along the road between Lake Tenaya and the lower end of Tuolumne Meadows. Seven Day Hikers first encounter them above Merced Lake on the trail to Vogelsang Camp. The finest hemlock stands are found on protected shelves not very far below timber-line. One such forest nestles close under Ragged Peak on the lateral moraines left by Mt. Conness glacier, about a mile from Young Lakes. Many of the trees there are three feet or more in diameter and estimated to be over one hundred feet high. In 1909 W. L. Jepson found a Mountain Hemlock near the base of Mt. Lyell that was eighty feet high and five and one-half feet in diameter four feet from the ground. This may be the record size tree for the species. In the northern section of the park there are often pure stands of hemlocks. This is especially true in the upper reaches of the Eleanor Creek Basin where, at around 9000 feet, all lakes are surrounded with gardens of well planted and well nurtured hemlocks. Some straggle up to the limit of tree growth as on Ragged Peak Ridge at about 11,000 feet and on Mt. Clark at 10,500 feet where they assume the prostrate forms of trees so characteristic of timber-line dwellers.



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