It is a monoecious shrub growing up to 1-1.2 m high. The bark is non-peeling and shiny red-copper colored. The leaves are rounded, 6-20 mm diameter, with a bluntly toothed margin. The leaves are a darker green on their upper surface. Leaf growth occurs after snow melt and become red in autumn. The wind-pollinated fruiting catkins are erect, 5-15 mm long and 4-10 mm broad.
B. nana is native to arctic and cool temperate regions of Greenland, Iceland,northern Europe, northern Asia and northern North America and it will grow in a variety of conditions. It can be found in Greenland, Iceland. Outside of far northern areas, it is usually found growing only in mountains above 300 m, up to 835 m in Scotland and 2200 m in the Alps. Its eastern range limit is on Svalbard, where it is confined to warm sites.
In general, it favors wet but well drained sites with a nutrient poor, acidic soil which can be xeric and rocky. B. nana has a low tolerance for shade.
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 with only scattered hairs, but coated in resin; leaves shorter (not over 12 mm long), often broader than long.
The genome of B. nana has been sequenced by a team of scientists led by Richard Buggs at Queen Mary University of London, using a plant from the Dundreggan Estate in Scotland owned by Trees for Life (Scotland).
- Ewing, Susan. The Great Alaska Nature Factbook. Portland: Alaska Northwest Books, 1996.
- 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
- Dwarf birch genome website
- Literature arising from the Expedition » Betula nana
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