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Larix Lyallii occurs in five isolated areas in the mountains of Northern Montana, between 113° and 115° E. long. and 47° 25' and 49° N. lat.

One of these localities was discovered by Prof. Elrod and myself in our ascent of the unexplored peak of St. Nicholas, which lies just west of the continental divide, about ten miles east of Nyack on the Great Northern Railway. Here about 1000 trees grow on a rocky precipitous slope, with a strictly northern aspect, and extend in scattered groves over about a mile of ground between 6600 and 7500 feet altitude. The tree is, owing to lack of moisture in the soil, unable to exist on the sunny southern slopes, where Pinus albicaulis thrives at similar altitudes. Separate groves of Engelmann's spruce accompany the Alpine larch. The largest tree measured 71 feet by 5 feet 2 inches; and another tree, felled by us, which was 8 inches in diameter, showed 220 annual rings, the sapwood with 25 rings being half an inch thick. Younger trees up to 40 feet high are gracefully pyramidal in shape, with wider branches than L. occidentalis; older trees have twisted and irregular branches and flattened crowns, the result of age, as is the case in all species of larch. The branches are remarkably brittle. On another part of the mountain, but still on the northern aspect, eighteen trees in two groups were seen at 8250 feet elevation, the tallest of which was only 10 feet high. The trees in Montana bore in 1906 only a few cones, but the crop in the preceding year had been plentiful. I procured only twenty or thirty seeds, which are now being raised at Kew. The cones in this species resemble those of the western larch in the manner in which they quickly cast their seeds in September.

The western larch in this region did not mingle with the Alpine larch, the former ascending, in company with Douglas fir, the northern slope up to 5900 feet; and between this elevation and 6600 feet, where the lowermost Alpine larch was found, no trees were growing.

Two other localities farther south are mentioned by Ayres, who states that on the summit of the continental divide (long. 113°, lat. 47° 25'), between the Sun river and Willow Creek, there is a fine forest of the species, with trees about 70 feet high and 15 inches in diameter. Twenty miles due west on the summit of the range north of Pend d'Oreille pass there are a few scattered trees.

In the Whitefish range and in the mountains between the Kintla and Chief Mountain lakes, the tree is common on northern slopes from the Canadian boundary line to about 15 miles south of it. In the Whitefish range, Ayres reports that the trees attain a maximum size of 80 feet by 6 feet in girth, the largest growing about the heads of basins where the snow lingers late into summer or lies in banks throughout the season. I visited the Whitefish range, which is a few miles from Fortine, on the Great Northern Railway, late in September, in company with Mr. Eastland, forest ranger, and at 7000 feet altitude could distinguish numerous groves of Alpine larch, extending over the mountains for an immense distance, as the foliage,