38 - EspritBonsaiInternational #101
Botanical^
Profile
Classification
Family: Betulaceae
Genus: Betula
Species: Betula pendula
Typical and progressive transition between white, smooth bark
and the blackened, cracked bark of a mature silver birch.
On these pioneer species,
the young slender branches
grow directly from the
trunk towards the light.
A speedy
pioneer
Silver birch
Identifiable by its lovely and
unparalleled light-coloured
bark, silver birch grows in all
types of environment.
Author:
Louis-Victor Bourdeau
S
ilver birch (also known as warty birch) is a
Eurasian species and is easily recognisable
by its smooth, white bark. It is a deciduous
tree and its Latin name, Betula pendula refers to
the pendulous, “weeping” aspect of its vegetation.
When the tree is very young, the bark is brown
and smooth that turns white, and then with age, it
becomes progressively dark grey and rough and
cracked.
Slightly sticky leaves
The young branchlets are glabrous, slender and
pendulous and carry little resinous warts, which
shed thousands of droplets onto the windscreens
of cars when they are parked under birch in leaf.
Measuring between 3 and 7 cm (1¼ and 2¾ in.)
long, the leaves are simple and alternate and some-
times a little sticky. They turn yellow in autumn
giving a luminous atmosphere to birch forests – the
last grand burst of light before the night of winter.
The buds are small and sticky. In spring, they are
a very light green.
It is a monoecious species with male and female
flowers (catkins) on the same tree. In mid-summer
the pollen of the male catkins is dispersed by the
wind onto the female catkins, which after inse-
mination, slowly mature and transform into scaly
pods that carry numerous, seeds. When the cat-
kins break open at the end of summer, the almost
weightless seeds are easily scattered in the wind.
At subalpine level
Silver birch is very similar to pubescent birch
(Betula pubescens), commonly known as downy
birch, and both species share part of the same
geographic range. As its name suggests, downy
birch bears smooth, downy shoots, whereas those
of the silver birch are hairless. Their habitat is the
same but the leaves are slightly different. The two
species can hybridise, but it is rare and no issue is
possible from the fruit of a hybridised plant.
Silver birch has an immense range covering
almost all the northern regions of the Eurasian
continent – from Ireland to eastern Siberia. It is
found in the northernmost limits for deciduous
trees and is one of the few species that can grow
at subalpine levels.
Downy birch is the archetype of the pioneer
species with all its characteristics. It colonises any
open space; it is not fussy about the type of soil,
and it can tolerate the lowest temperatrues. It is