A tree up to 230 ft high in its native forests, with a slender, lightly branched crown; trunk cylindrical, rarely exceeding 15 ft in girth; bark furrowed, reddish brown; young shoots downy. Leaves shortly stalked, set all round the branchlet, although more crowded on the upper side, linear, curved, 1⁄2 to 1 in. long, 1⁄20 to 1⁄16 in. wide, rounded at the apex, margins not toothed, sometimes grey-green, sometimes conspicuously blue-green. There are inconspicuous lines of stomata on both surfaces. Cones without stalks, rich purple when young, becoming red-brown; oval-cylindric, 11⁄2 to 3 in. long, 1⁄2 to 3⁄4 in. thick.
Native of western N. America, with its main area on or near the Pacific from Alaska to northernmost California, but also occurring in the Rocky Mountains from S.E. British Columbia to N. Idaho and N.W. Montana. It was described in 1832 from a specimen collected during the pioneering trans-continental journey of Lewis and Clark; and introduced to Scotland by John Jeffrey in 1852 for the Oregon Association. He sent only a small bag of seed, received in August 1852, but larger quantities were sent by the British Columbia Expedition in 1861-2.
Few conifers combine elegance and usefulness to such a degree as the western hemlock. In the right conditions it gains height at the rate of 2 to 3 ft a year and quickly makes a beautiful specimen when not crowded, but one needing plenty of room owing to the wide spread of its lower branches. It also yields timber of good quality and has been used in Britain to some extent as a plantation tree, especially since the Second World War. Like its companions in the forests of western N. America it likes a humid climate, and most of the finest specimens in the British Isles are to be found in the Atlantic zone, but it succeeds wherever the soil is not chalky nor inordinately heavy. The Lower Greensand seems to suit it very well, and there are three notable specimens on this formation in the Haslemere district, where the rainfall is higher than the average for S. England. It is tolerant of shade, and was used for under-planting of decrepit deciduous woodland until it was found to be subject to the butt-rot Fomes annosus when grown in these conditions.
The following are some of the many fine specimens measured recently by Alan Mitchell: Scone Palace, Perth, pl. 1866, 126 × 181⁄4 ft (1974); Dupplin Castle, Perths., pl. 1859, 134 × 121⁄2 ft (1970); Murthly Castle, Perths., pl. 1860, 139 × 123⁄4 ft (1970); Abercairney, Perths., pl. 1864, 120 × 111⁄4 ft (1974); Dawyck, Peebl., pl. 1860, 120 × 111⁄2 ft (1970); Strone, Argyll, pl. 1875, 124 × 143⁄4 ft (1976); Benmore, Argyll, 152 × 131⁄4 ft (1976); Cragside, Northumb., 138 × 123⁄4 ft + 121⁄4 ft (1974); Bodnant, Denb., pl. 1887, 131 × 123⁄4 ft (1974); Hafodunos, Denb., pl. c. 1856, 120 × 141⁄4 ft (1978); Drum Manor, Co. Tyrone, 108 × 183⁄4 ft (1976); Stourhead, Wilts, pl. 1871, 130 × 123⁄4 ft (1976); Knightshayes, Devon, 102 × 121⁄4 ft (1970); Honeyhanger, Shottermill, Haslemere, 92 × 13 ft (1971); Grayswood Hill, Haslemere, pl. 1881, 85 × 14 ft (1970); Lythe Hill, Haslemere, 112 × 121⁄2 ft (1969).