Canada hemlock Tsuga canadensis

Eastern Hemlock is an evergreen tree that may grow 40-80 feet tall or even to 100 feet in the pine family. It is native to eastern and central Canada and the USA and is found primarily in the mountains of NC and one small area of the Piedmont.  The leaves are flat with single needles that have two lines of white stomata on the underside. The bark is gray-brown and scaly in young trees. As the tree ages, wide ridges and furrows develop. In spring, small yellow male and small light green female flowers mature. The tree produces a 3/4-inch cone that matures in the fall. Its wood, although soft and brittle, is harvested for lumber and pulp. 

The conical shape, lacy effect of the leaves and branches the dip toward the ground give this tree a graceful effect. It grows best in part shade to full shade and can be used as an understory tree. It grows best in cool summer areas and doesn't tolerate the heat and humidity of the southeast. Eastern Hemlock needs moist but well-drained soils and doesn't tolerate drought.

Fire Risk: This plant has a high flammability rating and should not be planted within the defensible space of your home. Select plants with a low flammability rating for the sites nearest your home. 

Insects, Diseases, or Other Plant Problems:  A healthy plant in the proper environment has few problems. Potential disease problems for plants in the genus Tsuga include needle blight (needles turn yellow and die), canker, rusts, and rots. Potential insect problems include bagworms, borers, leaf miners, sawfly and spider mites. The foliage may scorch in very hot weather. A prolonged drought can be fatal to this tree.

Hemlock woolly adelgid (HWA) is a tiny (1/32”) sap-sucking insect (a relative of the aphid) that has recently become a serious threat to the survival of native hemlocks in the wild in the eastern United States. HWA was accidentally introduced into the U. S. in the 1920s from Eastern Asia. It has been known to exist in the Pacific Northwest since 1927 but was first observed in the forests of Virginia in the 1950s. It has now spread from Virginia into the southern and middle Appalachians. The inability to survive cold winters has so far substantially limited HWA’s northern spread to as far as Massachusetts, but northward expansion into much of New England is expected as winter temperatures continue to moderate. HWA has killed most of the old-growth hemlocks in the Great Smoky Mountains National Park and 95% of the hemlocks in Shenandoah National Park. HWA was discovered in Pennsylvania’s Allegheny National Park in November of 2013. Treatment of HWA is available (pesticides containing imidacloprid or dinotefuran), but control of this pest is very difficult.

Quick ID

• Branches in flat planes
• Linear leaves with 2 glaucous bands below
• Occasional leaf upside-down along minor twigs
• Pendulous ovoid cones from branches

VIDEO Created by Elizabeth Meyer for "Trees, Shrubs and Conifers" a plant identification course offered in partnership with Longwood Gardens.