Tsuga canadensis, also known as eastern hemlock,听eastern hemlock-spruce,听or听Canadian hemlock, and in the French-speaking regions of Canada as听pruche du Canada, is a听听听听to eastern North America. It is the听听of Pennsylvania.听Eastern hemlocks are widespread throughout much of the听, the听, the听, and听. They have been introduced in the听听and mainland Europe, where they are used as ornamental trees.
Eastern hemlock populations in North America are threatened in much of their range by the spread of the invasive听, which infests and eventually kills trees. Declines in population from hemlock wooly adelgid infestation have led to听Tsuga canadensis听being listed as Near Threatened on the听.
Eastern hemlocks are long lived trees, with many examples living for more than 500 years. They can grow to heights of more than 30 metres (100听ft), and are tolerant of shade, moist soil, and slopes. Hemlock wood is used in construction, and for听. Historically its bark was an important source of听听for the leather听听industry.听Eastern hemlocks are popular as ornamental trees, thanks to their tolerance of a wide variety of soil and light conditions, as well as their characteristic drooping branches.
Description
The eastern hemlock grows well in shade and is very long lived, with the oldest recorded specimen, found in听, being at least 554 years old.听The tree generally reaches heights of about 31听m (102听ft),听but exceptional trees have been recorded up to 53听m (174听ft).听The diameter of the trunk at breast height is often 1.5听m (4听ft 11听in), but again, outstanding trees have been recorded up to 1.75听m (5听ft 9听in).听The trunk is usually straight and听, but very rarely is forked.听The crown is broadly conic, while the brownish听听is scaly and deeply fissured, especially with age.听The twigs are a yellow-brown in color with darker red-brown听, and are densely pubescent. The听听are ovoid in shape and are very small, measuring only听1.5 to 2.5听mm (0 to听1鈦�8听in) in length. These are usually not resinous, but may be slightly so.
The leaves are typically 15 to 20听mm (0.59 to 0.79听in) in length, but may be as short as 5听mm (0.20听in) or as long as 25听mm (1听in). They are flattened and are typically distichous, or two-ranked. The bottom of the leaf is glaucous with two broad and clearly visible听听bands, while the top is a shiny green to yellow-green in color. The leaf margins are very slightly toothed, especially near the apex. The seed听听are ovoid in shape and typically measure听1.5 to 2.5听cm (5鈦�8听to 1听in) in length and听1.0 to 1.5听cm (3鈦�8听to听5鈦�8听in) in width. The scales are ovate to cuneate in shape and measure听8 to 12听mm (3鈦�8听to听1鈦�2听in) in length by听7.0 to 10听mm (1鈦�4听to听3鈦�8听in) in width. The apex is more or less rounded and is often projected outward. Twenty-four diploid听听are present within the trees'听.
