Today’s write-up and photographs of Larix lyallii are courtesy of Bryant, BPotD work-study student. He writes:
These subalpine (or alpine) larches were photographed on the northeast face of Mount Frosty in British Columbia’s E.C. Manning Provincial Park. Larix lyallii is one of my personal favorites for its unusual characteristics and its ability to survive higher altitudes and harsher conditions than most other conifers. Larix is one of the few genera of deciduous conifers (other deciduous conifers). In early/mid-September through early/mid-October in British Columbia, this species changes colour from green to a stunning golden-yellow. Larix lyallii grows in upper montane zones that would otherwise be considered alpine tundra (usually above the treeline of evergreen conifers), as well as on exposed rock outcrops. Its native range follows high alpine environments in southern (primarily southeast) British Columbia, southwestern Alberta and northern Washington, Idaho and Montana (distribution map).
Although trees of Larix lyallii are stunted by the long and harsh winters they endure, their trunks typically remain straight and upright (compared to displaying characteristics of Krummholz formation often seen among subalpine evergreen conifers). This is largely due to the deciduous characteristic, which helps to reduce the effects of winter desiccation and snow loading. The extreme hardiness of this species has helped it to become one of the longer lived species of conifer, with the known record holder being an individual 1,917 years old in Kananaskis, Alberta as of 2012!
Morphologically, Larix lyallii can grow up to 31m tall with a diameter at breast height of 215cm. As one might expect, larger specimens are generally found at lower elevations. The needles are quadrangular and grow in bunches of 30-40 atop abaxially keeled short shoots. They tend to grow in moist immature/rocky soil that is well drained. Plants grow at elevations between 1,900 and 2,380 metres, with slightly lower elevations in the North Cascades (1,830 to 2290m). Larix lyallii may also grow in association with Pinus albicaulis (whitebark pine), Abies lasiocarpa (subalpine fir), and Picea engelmannii (Englemann spruce) at the upper limits of their elevational distributions.