Eastern Hemlock - Tsuga Canadensis
Eastern Hemlock, or Canadian Hemlock (Tsuga Canadensis) This one of the most magnificent evergreen trees in Northeastern North America. They are often called “Redwoods of the East” because of their large size and can age to well over 500 years. Old growth hemlocks are truly a sight to behold, but are very rare. These trees were harvested by the million in the 19th century for their bark. The bark is rich in tannic acid, a main catalyst in leather tanning. The wood from these trees was often left to rot where the bark was stripped. Wood from Hemlock makes very good outside lumber products such as board and batten siding. The lumber is rot resistant and very insect resistant. Hemlock is also the state tree of Pennsylvania. Landscape use includes specimen trees as well as hedges. Recently two invasive insect pests are decimating our native Hemlocks. Hemlock Wooly Adelgid, and Elongate Hemlock scale are killing most trees that become infected. These pests feed on sap and are often both present on the same tree. Spider mites also attack trees that are drought stressed. Hotter summer temperatures are also taking their toll on tree mortality. These pests can be controlled in the landscape but are very difficult to control in a forest setting. Treatments are costly and usually need repeated for several years. The use of Hemlock in landscaping plans have been diminished due to these pests. Hopefully this species will endure and remain for several more centuries.