Tsuga mertensiana commonly known as Mountain Hemlock is a tree of the upper slopes of the mountains of western North America, its range extending from Alaska to California. It grows in moist soils in forests, thin-peated spruce mires and rocky areas, favouring cool, moist, northern slopes. It is often considered the beauty of the genus. Unlike the other species, mountain hemlocks concave needles are the same colour on both surfaces and spread in all directions. This gives the tree an attractive, fluffy, cedar-like appearance. The needles are wax-covered and the tree generally bluish in colour, with some provenances a strong blue-grey. The cones, looking rather like spruce cones, are larger than those of the other hemlocks.