Betula papyrifera the genus "Betula". Several varieties are recognized "Betula papyrifera" is mostly confined to Canada and the far northern United States. It is found in interior (var. "humilus") and south-central (var. "kenaica") Alaska and in all provinces and territories of Canada, except Nunavut, as well as the far northern continental United States. Isolated patches are found as far south as the Hudson Valley of New York and Pennsylvania, as well as Washington. High elevation stands are also in mountains to North Carolina, New Mexico, and Colorado. The most southerly stand in the Western United States is located in Long Canyon in
Alnus viridis Alnus viridis Alnus viridis (green alder) is an alder distributed widely across the cooler parts of the Northern Hemisphere. It is a large shrub or small tree 3–12 m tall with smooth grey bark even in old age. The leaves are shiny green with light green undersurfaces, ovoid, 3–8 cm long and 2–6 cm broad. The flowers are catkins, appearing late in spring after the leaves emerge (unlike other alders which flower before leafing out); the male catkins are pendulous, 4–8 cm long, the female catkins 1 cm long and 0.7 cm broad when mature in late autumn, in clusters