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Siberian larch, or Larix sibirica, is one of a handful of larch species across the often-frigid northern hemisphere. Though this conifer can be found in 2011 around the globe, it still is largely contained to the forests of Eastern Siberia, where it makes up about 75 percent of the total tree population. Long prized in construction for its decay-resistant wood, this tree is also well-established as an herbal remedy that has recently gained scientific credence as an immune system booster.
In Russia about one of every two coniferous trees is a Siberian larch. That figure grows to about three in every four trees in East Siberia and other Baltic regions of Russia's northeastern territories. In other parts of the world, different larch species are more prominent. The European larch, or Larix decidua, is far more common in the Arctic regions there. Across the Atlantic Ocean in the western hemisphere, the American and western larches — L. laricina and L. occidentalis, respectively predominate.
In the United States, the Siberian larch is recommended for landscaping in only the United States Department of Agriculture's hardiness zone two. Mainly consisting of Alaska and parts of Minnesota, this region is marked by average minimum temperatures between -40 and -50°F (about -40 to -46°C). With moderately moist soil under full sun, these trees can grow as tall as about 60 feet (about 18 m). Though its stubby needles show green in warmer months, they turn brown and shed in fall, leaving the branches largely bare through winter.
Builders started using Siberian larch sometime during the Middle Ages, between the fifth and 15th centuries. Not only is the wood known for its density that beats out other hardwoods like pine and spruce, but its planks also hold their shape and function longer. The wood's most-touted attribute is a superior resistance to decay. All of these characteristics have led to this species being used for outdoor structures like bridges, dams, utility poles, railroad ties and fence posts.
Construction and landscaping are not the only uses for Siberian larch. For centuries, herbalists have prepared a tincture of larch bark that is rich in a compound called arabinogalactan. Though this extract has been used as a homeopathic diuretic, antibacterial agent and stimulant, its alleged immunity-boosting qualities appear to be of utmost interest to modern science. Some cellular research has indicated that larch bark may spur white blood cells into greater action, however, another study of lab rats refuted this by showing how white blood cells in bone marrow actually decreased in a week's time after daily arabinogalactan injections began.