Our only native evergreen that tolerates heavy shade, eastern hemlock is usually found in the forest understory -- however given sufficient space and sunlight, this tree will easily reach heights of  70' or more.
Eastern hemlock is an important wildlife species.  Many forest creatures depend on this tree for food, browsing the twigs, bark and seeds.  Equally important is the shelter provided, especially during winter.  As snow falls and weighs down the boughs, insulated tents are created beneath where animals rest and are warmed by their own body heat.

Hemlock wooly adelgid, a tiny, fuzzy insect accidentally imported to the U.S. in 1924 from Asia began feeding on eastern hemlock trees with devastating results.  Virtually every state on the eastern seaboard has reported infestations of this pest, frequently with fatal results.  Until recently, New Hampshire's hemlock trees were unaffected by HWA, but was discovered in Portsmouth in 2000, and in Peterborough in 2001.  Infestation usually occurs as a result of exposure to imported, infected nursery stock.  HWA faces a challenge in the form of the newly discovered exotic adelgid predator, Pseudoscymnus tsugae, which feed voraciously on all growth stages of HWA.  Concerns about the cure being worse than the disease prompt the scientific community to extensively test predators before they are released.