Ten species of hemlock (Tsuga) are found across North America and Asia. When young, all species have a tell-tale drooping top or leader. The largest species, Western Hemlock (Tsuga heterophylla), is a common forest tree in the lowland Northwest. A popular landscape tree, Mountain Hemlock (Tsuga mertensiana) is native to higher elevation forests of the Northwest. Check out some of the other hemlocks in the Arboretum collection!

1)      Tsuga dumosa                                                                       Himalayan Hemlock

Like most hemlocks, this tree grows in cool, temperate forests with high rainfall and humidity. This species commonly reaches 80 feet and is an important forest tree in China where it contributes to the giant panda habitat. Pandas use large hollow trees as dens. A young specimen can be seen along the Arboretum Loop Trail at the southern end of the park.

Joanna Long

2)  Tsuga canadensis                                                                        Eastern Hemlock

An important component of eastern North American forests, this tree has been ravaged by the Hemlock wooly adelgid, a pest from Asia. The Washington Park Arboretum is the location of ongoing studies about the hemlock wooly adelgid and its predators, including a small beetle (Laricobius nigrinus), native to the Northwest and now introduced on the East Coast as a biological control. Several species and cultivars can be found at the northern edge of the Magnolia Collection.

Joanna Long

3)  Tsuga chinensis                                                                          Chinese Hemlock

This large tree (reaching up to 150 feet) is resistant to the hemlock wooly adelgid and is being used in landscapes of the eastern U.S. to replace Eastern Hemlocks. Similar to our Mountain Hemlock, the Chinese Hemlock often grows on mountain ridges. A couple of these trees can be seen at the northern edge of the Magnolia Collection.

Joanna Long

4)  Tsuga caroliniana                                                                      Carolina Hemlock

This rare conifer is confined to a small area of the southern Appalachian Mountains. Traditional uses by the Cherokee include using the inner bark for basketry and dye. A specimen can be found at the northern edge of the Magnolia Collection.

Joanna Long

5)  Tsuga sieboldii                                                                 Southern Japanese Hemlock

This tree grows in the maritime, mixed conifer forests of Japan and is a popular landscape tree there. The genus name, Tsuga derives from the Japanese name for this tree. A few of these trees can be seen in the north end of the Pinetum.

Joanna Long