If you are out and about looking at plants this week then just
about wherever you are in lowland Britain (see defra website for map) you are likely
to see this one. Whether you find yourself in a city, the countryside or
speeding up the M6 – it will be there. It was introduced to the UK by Victorian
plant hunters in 1839 and attractive though it may be it has a deadly
combination of highly efficient annual reproduction through exploding seed pods
and an easy monoculture, which it achieves by shading out other plants. Seed is
projected some distance from the parent plant by the action of the ripening pod
when touched or disturbed by the breeze. Add to this the very long season of
seed ripening and dispersal – from June to October – and you have a potentially
massive problem for our countryside, parks and gardens. The worrying thing is
the speed at which this plant has become omnipresent. When I first started
getting to know the Mersey Valley park in south Manchester – about 7 years ago –
the banks and hedgerows were a mix of all the usual native annuals and
perennials and shrubs. Now huge areas are dominated by this single species,
with all the consequences this brings for diversity of plant and animal life.
It is known to colonise canal and stream edges but this Autumn I have seen it
in huge numbers in wetlands, on woodland margins, road embankments and field
margins.
Efforts have been
made to control some of these populations but ‘balsam bashing’ is very labour
intensive and does not begin to address the scale of this problem. The fact of
seed spread by water, feet and tyres means that the answer can only lie with a central
government initiative. The defra website will tell you it is an offence to
plant it or introduce it in to the wild, but I would respectfully suggest that
this is unlikely to make any impact whatsoever on its continuing spread.
If you want facts rather than my opinion have a look at the
defra pages here. There are also local action groups listed through that site, though
as these don’t join up and their activities are not governed centrally its hard
to see what difference they will make.
Here are my photos showing the plant, flowers and pods before and after expelling their seed.
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