Tsuga(redirected from Hemlock trees)
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(hemlock), a genus of evergreen coniferous trees of the family Pinaceae. The shoots are pendant and slender. The needles, which are on short petioles, are mainly flat, linear-lanceolate, and blunt and notched at the apex. The pollen spikes (mi-crostrobiles) are solitary, and the pollen has no air sacs. The cones, which are woody and pendant and measure 1.5–2.5 cm in length, mature in the year of flowering and fall off completely. The cone scales are small, and the seeds are winged. Propagation is by seeds and cuttings. Hemlocks are moisture-loving and shade-tolerant. They are raised as ornamentals and for their lightweight wood, which is used mainly to manufacture paper. The bark contains tannins.
There are about ten species (according to other data, 15), distributed in the Himalayas, China, Japan, and North America. Six species have been introduced into the USSR, including the eastern hemlock (T. canadensis) and T. diversifolia. The eastern hemlock is native to North America. A tree measuring about 30 m in height, it has arching branches and pectinate needles. T. diversifolia is native to Japan. A tree measuring up to 25 m tall, it has horizontal branches and needles of varying length (1 to 1.5 cm) that protrude in all directions. The species is found outside Sukhumi and in Western Europe, where it grows in the form of a shrub.
REFERENCEDallimore, W., and A. B. Jackson. A Handbook of Coniferae and Ginkgoaceae, 4th ed. London, 1966.
T. G. LEONOVA