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Betula nana

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Betula nana, the dwarf birch,<ref>Template:PLANTS</ref> is a species of birch in the family Betulaceae, found mainly in the tundra of the Arctic region.

Betula nana in Norway. September 2012. 1000m ASL

Description

It is a monoecious shrub growing up to 1–1.2 m high. The bark is non-peeling and shiny red-copper colored.<ref>Ewing, Susan. The Great Alaska Nature Factbook. Portland: Alaska Northwest Books, 1996.</ref> 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.

Distribution

Betula 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. 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 northern range limit is on Svalbard, where it is confined to warm sites. In the UK Betula nana is at its southern range limit, with many populations having declined significantly in recent decades<ref>Template:Cite journal</ref>.

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.

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 with only scattered hairs, but coated in resin; leaves shorter (not over 12 mm long), often broader than long.

Genome

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).<ref name=Wang2013>Template:Cite journal</ref>

References

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External links

Betula nana photographed north of the village of Upernavik Kujalleq, north-east of the mountain Kingigtoq, western Greenland

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