Betula nana (Dwarf Birch) is a species of birch in the family Betulaceae.
Description
Diapensia lapponica with a branch of dwarf birch, Nunavut, July 1996
It is a shrub growing to 1-1.2 m high. The bark is non-peeling and shiny red-copper colored.[1] The leaves are rounded, 6-20 mm diameter, with a bluntly toothed margin. The fruiting catkins are erect, 5-15 mm long and 4-10 mm broad.
Distribution
B. nana is native to arctic and cool temperate regions of northern Europe, northern Asia and northern North America and it will grow in a variety of conditions. Outside of far northern areas, it is usually found only growing in mountains above 300 m, up to 835 m in Scotland and 2200 m in the Alps. Its northern range limit is on Svalbard, where it is confined to warm sites.
Ecology
There are two subspecies:
- Betula nana subsp. nana. Canada (Baffin Island), Greenland, northern Europe (south to the Alps at high altitudes), northwestern Asia. Young twigs hairy, but without resin; leaves longer (to 20 mm), usually as long as broad.
- Betula nana subsp. exilis. Northeastern Asia, northern North America (Alaska, Canada east to Nunavut). Young twigs hairless or only with scattered hairs, but coated in resin; leaves shorter (not over 12 mm long), often broader than long.
References
- ^ Ewing, Susan. The Great Alaska Nature Factbook. Portland: Alaska Northwest Books, 1996.
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