Belfast Botanic Gardens Tree Archive
This is one of a series of short articles about trees in the Belfast Botanic Gardens compiled by the Friends group. The tree tag number relates to the small aluminium discs, usually fixed on the tree trunk, 2 to 3m above ground level.
Downy birch or white birch
This birch is quite like the silver
, but extends far further north. It is the only substantial deciduous
tree in Iceland and Greenland and also extends across Europe into Asia. It
is more tolerant of waterlogged soils than the silver birch and is much commoner
than the latter in Ireland. The first woodlands to spread across Ireland after
the last ice age were birch woods. Where the two trees grow together their
shape is distinctive. In Belfast Botanic Gardens, the two species grow either
side of the path close to the park works entrance (near the bird feeders).
The Silver birch branches are much more weeping than the downy birch. The
leaf shape is also slightly different as illustrated on our silver
. The species are cytologically different as the silver birch
is diploid and the downy birch is tetraploid. The seeds have papery wings
and both the seeds and the distinctive shaped seed-scales are found in lakes
and bogs dating from the earliest post-glacial forests in Ireland. There are
a number of downy birches in the Belfast Botanic Gardens - the tag and reference
above refer to a group of three at the south end of the main lawn.
|Early morning sun catches a downy birch in Belfast
||Leaf of downy birch
|Bark of downy birch
||Seeds and a seed scale of downy birch.
Photos taken in Belfast Botanic Gardens in 2009 and 2010. Copyright: Friends of Belfast Botanic Gardens.
Click here to view the rest of the tree archive
reference (1): The Trees of Britain and Northern Europe by Alan
Mitchell and John Wilkinson. Collins, London 1991.