Betula occidentalis odorless when scraped. The leaves are alternate, ovate to rhombic, long and broad, with a serrated margin and two to six pairs of veins, and a short petiole up to long. The flowers are wind-pollinated catkins long, the male catkins pendulous, the female catkins erect. The fruit is long and broad, composed of numerous tiny winged seeds packed between the catkin bracts. The identity of similar birches in Alaska is disputed; some include them in "B. occidentalis", while others regard them as hybrids between "Betula neoalaskana" and "Betula glandulosa". Some Plateau Indian tribes used water birch to treat pimples and
Mesoraphidiidae genera. Mesoraphidiidae are similar in overall appearance to modern snakefly species, having an elongated prothorax, giving a snake-like profile and from which the common name snakefly is derived. The family was likely tree-dwelling by nature, with larvae being active predators in trunks and branches. Female mesoraphidiids, where known and complete enough, have a long and densely annultated ovipositor which would have been used to lay eggs in crevices of bark. The family was restricted to the Northern Hemisphere, living in the warm temperate and paratropical forest belt that covered portions of Eurasia and North America. As currently described, Mesoraphidiidae contains