TREE OF THE MONTH
A taste of the
East, consumed
by the West
Dr Terry Mabbett explores the history and properties of
Japanese maple (Acer palmatum), a native of East Asia,
introduced into the West relatively late in the day.92 AUGUST 20 19 FORESTRYJOURNAL.CO.UKB
ROUGHT to Europe in the 1800s,
Japanese maple subsequently
established a firm foothold in Britain,
first in specialist gardens modelled on
those in Japan, but more recently as a
common-or-garden tree.
Acer palmatum is more instructively called
‘palmate maple’ due to the distinctive leaf
form easily mistaken for that of a compound
palmate leaf (leaflets arising from the same
point of insertion), but in truth a deeply
divided, simple leaf. However, the name
Japanese maple is something which the
gardening public can easily relate to and, as
such, has endured.
The name Japanese maple is entirely
appropriate because it was the Japanese who
first used the trees in artistic landscapes.
Perhaps the reason Japanese designers
chose A. palmatum is because you can’t
appreciate the full beauty of this shrub or
small tree unless it is planted within its own
space. An aim of Japanese gardens is to
‘borrow’ the wider landscape around them.
And if there is a naturally good view
to capture, how better to frame
it than with some choice
Japanese maple? Highly
attractive foliar canopies
grab the near vision
while low, mound-like
tree canopies allow
observers to see beyond
and into the surrounding
landscape.BOTANY AND
ECOLOGY
With over 1,000 cultivars now
growing around the world, it is easy to
lose sight of the original wild, native type, if
there was ever one at all. There was and still
is a ‘wild type’ native to Japan but also China,
the Korean peninsula and southeast Russia.
Wild A. palmatum is a feature of woods
and thickets in a wide range of soils and
exposures, found at up to 3,000 m elevation in
central and and southern Japan.A. palmatum typically takes the form of a
shrub or small tree, reaching heights of 6 to
10 m (and, rarely, 16 m) as an understorey
species in shady woodlands. Trees are
usually single stemmed, but sometimes have
multiple stems, joining up close to ground
level. Bark on trunks and main branches is
grey and smooth, while twigs are covered
with smooth, shiny and showy bark.
The leaves are 4 to 12 cm in length and
width, deeply divided, with five to nine
acutely pointed lobes. Autumn leaf colour is
highly variable, depending on cultivar, with
various shades of yellow, purple, orange and
red, and is highly reliable as trees hold onto
their leaves late into autumn.
Flowering begins in May with flowers
borne in small cymes (flower clusters), with
each flower having five red or purple sepals
and five whitish petals. The fruit is a pair of
winged samaras, each 2 to 3 cm in length,
with a seed which is 6 to 8 mm long.
A. palmatum as a commercial entity is
notable for its exceptional variation, but
even the wild native type displays
considerable inherent genetic
(and therefore phenotypic)
variation in foliar trait,
including leaf size,
shape and colour (and
in overall canopy form,
which can vary from
upright to weeping).
Indeed, this extremely
high level of variation
within the wild natural
population is a key
reason why early Japanese
botanists and gardeners were
attracted to the tree and able to
exploit it within the landscaping sector.CULTIVATION AND USES
A. palmatum has been part of Japanese
culture for centuries. It was first mentioned
in the 7th century but did not start to spread
into other parts of the temperate world until
the1800s. Carl Peter Thunberg, a Swedishbotanist and medical doctor who travelled
throughout Japan in the late 18th century, sent
home drawings of a small tree that would
eventually become the best-known feature
of the sophisticated art which typifies the
oriental garden. Thunberg bestowed the
name ‘palmatum’ after the hand-like shape of
its leaves, perhaps getting the idea from the
age-old Japanese names kaede and momiji,
referring, respectively, to ‘hands of frogs’ and
‘hands of babies’.
Plant hunter J. R. Reeves is believed to
have introduced A. palmatum into England
in 1832. However, owing to Japan’s embargo
on trade, the number of plants reaching ourUniformly green-leaf
cultivars are especially
attractive in late
spring when at their
most verdant green.Below: Japanese maple
bark is essentially
smooth and grey with
some interesting
patterns depending
on cultivar. Green-leaf
cultivar shown here.Below inset: Japanese
maple leaves have five
to nine sharply-pointed
lobes. Green-leaf
cultivar seen here
in early May 20 18
with flower cymes
(clusters).