CONIFERS OF THE ROCKY MOUNTAIN REGION. 13 



as Tsuga heterophylla. He first observed the tree on the shores of 

 Puget Sound in 1792. 



The first technical name, "Abies heterophylla Rafinesque," applied 

 to western hemlock, was published in 1832. The present accepted 

 name, Tsuga heterophylla (Raf.) Sargent, which is based on that of 

 Rafinesque, was, however, not established until 1898. From 1867 

 to the latter date western hemlock was generally known to botanists 

 as "Tsuga mertensiana Carriere," which was published in 1867. 

 But this name, which is based on "Pinus mertensiana Bongard" 

 (published in 1831), Prof. C. S. Sargent has shown must be applied 

 to our mountain or black hemlock. 20 



DISTINGUISHING CHARACTERISTICS. 



Western hemlock is a large forest tree. Its tall, clean, smooth- 

 looking trunks, fine foliage, and drooping branchlets distinguish it 

 from all of its associates. The trunks taper very gradually. As a 

 rule, the base of the trunk is not greatly enlarged, but many trees 

 from seedlings grown on logs and stumps are irregularly buttressed. 

 Forest-grown trees have small, narrowly pyramidal crowns of slender 

 branches, and are from 125 to 175 feet high and from 2 to 5 feet in 

 diameter. Occasionally trees are found which are nearly 200 feet 

 high and 8 or 9 feet in diameter. The bark of the larger branches 

 and young trees is thin, finely scaly, and russet-brown; that of old 

 trunks is about 1 J to 1| inches thick, hard, deeply furrowed, and of a 

 dark, russet-brown color tinged with red; the main wide, flat ridges 

 are irregularly connected with one another bj^ narrower diagonally 

 disposed ridges. 



In color the foliage is a deep, glossy yellow-green. It clothes the 

 twigs thickly, but has a rather thin appearance because of the small 

 size of the leaves. The leaves (PL IV) appear to grow mainly from 

 two opposite sides of the branchlets — somewhat like the teeth of a 

 comb. They are flat, with a central groove on the upper side, have 

 rounded ends, and short, distinct, threadlike stems, and vary in 

 length from about one-fourth to seven-eighths of an inch. 21 The 



20 Western hemlock was introduced into cultivation in Scotland by John Jeffrey in 1851 (Malcolm Dunn, 

 in Journ. Royal Hort. Soc, XIV, 78, 1892). Mr. Dunn (op. cit.) states that this tree was soon afterwards 

 planted elsewhere in the British Isles, where it generally seemed perfectly at home. The large number 

 of trees located by Mr. Dunn vary in age from about 20 to 40 years and in height from 35 to 72 feet, with 

 diameters ranging from 15 to 25 inches. According to Elwes and Henry (The Trees of Great Britain and 

 Ireland, II, 236, 237, 1907, under "Tsuga albertiana") the largest tree in England is said to have been planted 

 in 1856, and in 1907 was 94 J feet high and about 33 inches in diameter. Western hemlock is said to thrive 

 also in temperate parts of Europe. A trial of this hemlock is being made at the Letchworth Park Forest 

 and Arboretum, Wyoming County, N. Y. Seedlings raised from seed planted there in 1914 have survived 

 two winters and appear to be hardy. 



2i The German dendrologist Beissner has described (Handb. Nadelh., 404, 1891) a garden form of the 

 western hemlock as " Tsuga mertensiana macrophylla," which he distinguished by its longer and broader 

 leaves. This form, which originated in France, appears not to be cultivated in the United States. Owing 

 to the fact that a similar broad-leafed form of our eastern hemlock (Tsuga canadensis) was previously named 

 "macrophylla," this garden form of the western hemlock was renamed Tsuga heterophylla latifolia Sudw. 

 in 1898. Another garden form, with silvery- white young shoots, doubtless originated in a European nursery, 

 and as yet unknown in cultivation here is "Tsuga mertensiana argenteo-variegata Hort." (Beissner, op. 

 cit.,ed. 2, 94, 1909). 



