Scientific Name
Larix sibirica
The Siberian larch shares with the North American larch (aka tamarack) an extreme tolerance for cold winter weather, surviving temperatures of −50°F. Its native range is the northern parts of Russia beginning near the border with Finland and proceeding east into Siberia halfway to the Pacific Ocean, at which point it is replaced by a different larch species. It grows as far north as 74 degrees north latitude, which is 3 degrees closer to the north pole from the north coast of Alaska. Like other larch trees, this one drops its needles every fall and grows new ones in the spring. These needles grow either one by one on the new branch tips or in thick bunches on short side bumps called spurs. The foliage turns yellow in the fall before dropping. These are very tall trees in nature, well over 100 feet and possibly 200 feet, but in cultivation are far shorter with perhaps 50 feet being normal. Not that many have been grown in our region, so we cannot be certain about their mature height; the current Colorado champion is 36 feet tall. The tree’s form is pyramidal with side spreading branches. The 1 to 2 inch seed cones are upright on the branches and progress from green to red to brown when mature. Larches can be difficult to distinguish from each other. In this case, the Siberian has hairy new growths whereas the other larch at Regis, the European, has smooth growths.
Given the cold hardiness of this tree as mentioned, there is no issue about surviving a Colorado winter, but summers are far warmer and longer than in its native habitat and that can be stressful. The same is true with the North American tamarack, which is rarely seen along the Front Range. Another issue is that the Siberian larch tends to grow new greenery quite early in the spring and sometimes has it killed by a sudden sharp freeze, after which it must grow a new set of needles. Several larger larches of this species may be seen growing nicely at Denver Botanic Gardens.