Dwarf Birch
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Dwarf Birch (Betula nana) is a species of birch in the family Betulaceae, native to arctic and cool temperate regions of northern Europe, northern Asia and northern North America. 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.
It is a shrub growing to 1-1.2 m high. 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.
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
- Trees for Life: [Species profile] and [Reference list]
- [Flora of North America: Betula nana]
- [Betula nana Distribution map]
- [Conservation Genetics and Population History of Betula nana etc., in Svalbard]
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