The common name of Larix occidentalis is the Western Larch and is in the Pineceae family. It is native to the mountain valleys and lower slopes from southeastern British Columbia to southwestern Alberta as well as southward from eastern Washington to western Montana. It is also found growing naturally in northern Oregon and Idaho. Even though it is prevalent in the community, it is not considered a climax species, but rather a long-lived early successional species. Some trees have been reported to being over 900 years old.
Western larch is a monoecious and deciduous conifer that can grow up to 55m tall and 2m DBH. A third to one half of the total height is usually branch-free but some trees growing in the open can have branches growing to a couple feet above the ground. When the tree is young, the reddish brown bark is thin and scaly and as it grows older, it thickens (to around 15cm at age 50 and 35cm at age 100) and becomes furrowed and plated. The crown of the tree is short and pyramidal with nearly horizontal branches. Its linear, light green needles are 2.5-5.0cm long and are present in circular clusters (15-30 needles) on spur shoots on older twigs. In autumn, the needles turn bright yellow. Its pollen cones are 1cm long and are yellow to yellow-green in color. The seed cones are 2-3cm by 1.3-1.6cm and are purple to reddish brown when immature, turning brown when matured. Prominent yellow to orange bracts can also be observed on the seed cones. The seeds are reddish brown with a 3mm body and a 6mm wing.
This conifer has an extensive root system to stabilize it and as a result, it is quite wind resistant. As well, mature Western Larchs are incredibly fire-resistant. It is considered the most fire-resistant tree in British Columbia, Washington, Oregon, and Idaho. After a fire, it is common to see a few mature Western Larch trees as the only survivors in the area. It has many adaptations that contribute to its ability to survive fires: a thick bark to protect its cambium from overheating, a mostly bare trunk that minimizes the chance of flames travelling up the tree branch by branch, and because the tree is deciduous, it is more adapted to losing its needles in a fire.
The Larix occidentalis, with its long bare trunk, dense wood, and very high growth rate, is one of the most important timber trees in western North America. The durable and decay-resistant wood is used in construction framing, railway ties, and other carpentry uses. Native Americans used this tree to treat tuberculosis, colds and coughs, and sore throats. The bark contains arabinogalactan, which Native Americans chewed as gum and we now use for offset lithography and in pharmaceuticals, paint, and inks.
References
Klinkenberg, Brian. (2012). E-Flora BC: Electronic Atlas of the Plants of British Columbia [Online]. Lab for Advanced Spatial Analysis, Department of Geography, University of British Columbia, Vancouver. Retrieved from: http://linnet.geog.ubc.ca/Atlas/Atlas.aspx?sciname=Larix%20occidentalis
Scher, Janette S. (2002). Larix occidentalis. In: Fire Effects Information System. [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Retrieved from: http://www.fs.fed.us/database/feis/plants/tree/larocc/all.html
Earle, Christopher J. (2011). The Gymnosperm Database: Larix occidentalis [Online]. Available from: http://www.conifers.org/pi/Larix_occidentalis.php