Part of
birch genus Betula
in
alder / birch / hazel / hornbeam family Betulaceae
in
bayberry / beech / birch / oak / walnut order Fagales.
Native to the arctic tundra, and subarctic. Definitely native to 🇺🇸 Alaska, 🇨🇦 northern Canada, and 🇬🇱 Greenland. Some sources include Asia, which we interpret as 🇷🇺 Siberia, making it circumpolar.
▭ 🌎︎ Map (North America, Central America). 
Thus, the shortest of all the birches. By a lot! Tree is never more than boot-top- or waist-high, and the leaves are tiny.
Shares the same climate and habitat as
gray willow Salix pulchra
and
marsh Labrador tea Rhododendron tomentosum, formerly Ledum palustre.
Uses by native peoples
(Ethnobotany database)
Betula hosts caterpillars of 413 species
of butterflies and moths, in some areas.