In 1937 the climber, explorer and plantsman F.S. Smythe
travelled to the remote Bhyundar Valley in the (then) British Protectorate of
Sikkim in the Himalayas. In the course of his expedition he noted that, “...
where extensive grazing is permitted, the smaller and tenderer plants are soon
eliminated and in their place spring up a tall knotweed (Polygonum polystachyum) and an even taller balsam (Impatiens Roylei). Once these two plants
have got a hold of the ground, pastureland is permanently ruined and I noticed a
number of places in the Bhyundar Valley where this had occurred.”
Those parts of the valley that were not over-grazed were
smothered in wonderful displays of wild flowers: Androsaces, Saxifrages, Sedums, Potentillas, Geums, Asters, Gentians and many more.
Polygonum polystachyum,
now called Persicaria wallichii, is
Himalayan Knotweed; it does occur in Britain, as a garden escape, but doesn’t
appear to be particularly common (yet!) but in many American states it’s
classified as a pernicious weed. Its
close relative, Fallopia japonica – Japanese Knotweed is a
pernicious weed in this country and has a fearsome reputation for being hard to
eliminate.
Impatiens Roylei,
now called Impatiens glandulifera, is
Himalayan Balsam. It is just as invasive in Britain as it is in its homeland
(of Northern India), and probably even more so because here it doesn’t require
overgrazing in order for it to take a hold. It is now found all over Britain,
along rivers, streams and canals and in damp places and on waste ground. Whereas the two Knotweeds described above are
perennials with extensive and invasive rootstocks, Himalayan Balsam is an
annual which regenerates every year by seed. It is reckoned that its seeds can
remain viable in the ground for around two years. Once this plant’s long,
tear-dropped shaped seed pods are ripe, in late summer, they explode at the
slightest touch and fling out seeds with such force that they can travel many
yards from the parent plant.
On the Chorlton Ees and Ivy Green Local Nature Reserve
Himalayan Balsam is found in abundance along the banks of Chorlton Brook, where
the seeds have probably been deposited on the banks following floods. The
exploding seed pod mechanism has then allowed the plants to spread out sideways
and beyond the confines of the brook’s banks.
The Sunday before last (01.07.2012) members of FoCM
attempted to remove as much Balsam as possible from the edge of a small Birch
and Willow copse. We chose this site because the copse provides a habitat for a
rather scarce species of fern called Narrow Buckler Fern (Dryopteris carthusiana), which we believe it is important to
conserve.
So how did I.
glandulifera get to the UK and become so invasive? This turns out to be a
rather surprising story. It was first introduced into the UK in 1839, when Dr
John Forbes Royle, an Indian born British botanist, sent seeds to Kew. By 1855
it was first found growing wild in Hertfordshire and Middlesex. The Manchester
botanist, Leo Grindon mentioned it in his ‘Manchester Flora’ of 1859: “The Impatiens coccinea (sic), a tall and
weedy plant, with flowers of a dull red colour, is rapidly disseminating itself
...” (I’m not sure where Grindon got that name – but it’s almost certainly yet
another defunct synonym for I.
glandulifera – and there’s really nothing else that it could be). So rapidly did Himalayan Balsam ‘disseminate’
itself that by 1932 it was found in 27 out of 112 British Vice Counties (for
the purposes of biological recording Britain is divided into standard,
approximately equal area zones called ‘Vice Counties’); by 1962 it was found in
47 VCs and by 1993 it was found in 107. This relentless spread was probably due
to the fact that the species proved to be very attractive to gardeners - who
saw it as exotic looking, attractive and easy to grow (surely, a monumental
understatement!).
During the course of
the 19th century the influential gardener, William Robinson
developed his concept of the ‘Wild Garden’. This was, basically, a reaction
against Victorian regimented bedding schemes. Robinson was aiming for as
‘natural’ a looking garden as possible. This was mainly an aesthetic concept,
and had little to do with wildlife or ecology. In his planting schemes he used
many of the plant species that were pouring into Britain from the temperate
parts of the world. Among the species that he selected were such ‘horrors’ as
Giant Hogweed, Japanese Knotweed and – you guessed it – Himalayan Balsam; and
we’re still living with the consequences!
But we can’t blame Robinson alone. In 2000 Ian D. Rotherham, of Sheffield Hallam
University, presented a paper on the spread of Himalayan Balsam to a conference
on Ecology in Birmingham. Rotherham, and his colleagues, had initiated a study
of the spread of the plant – first in the Sheffield area – and then in the rest
of the UK. They published a request for information, from members of the public,
in the local and national media (mainly gardening magazines). They received
over 200 replies. It became obvious that many people like this plant – and have
deliberately spread it! For example:
In 1948 Miss Welch collected seed near Sheffield and
released it by a river on the Isle of Wight.
In the 1990s Mrs Norris of Surrey introduced seeds to ‘spare
land’, gave them away to a passersby, a work colleague and an Irish market
gardener friend, scattered seeds in local woods and took them on holiday to
France and Spain (!)
I believe that these stories reveal a worrying attitude to
the environment, which may be one of the roots of our present biodiversity
problems, and can be summed up thus: “My local environment is of no account,
and contains nothing of interest, and I can introduce anything I like into it
with no significant consequences.” The remorseless spread of I. glandulifera, and its deleterious
effects on local environments all over the UK, demonstrates just how wrong this
attitude is!
During his Bhyundar Valley expedition in 1937 F.S. Smythe had
the following experience:
“For a little distance we followed a rough shepherd’s track
but presently lost it and had to force our way through a wilderness of
pink-flowered balsam (Impatiens Roylei)
growing fully eight feet tall. Had it not been for the labour we might have
appreciated the beauty of these flowers which covered acres of the valley floor
in a sheet of bloom; as it was, we were heartily glad to regain the path,
dripping with sweat after the unusual exercise.”
It so happens that I know exactly what he meant! A couple of
years ago I was making my way from one part of Urmston Meadows to another; this
involved negotiating a narrow track – much of which was ankle-deep in mud. To
my left was a Himalayan Balsam ‘thicket’ - which was easily eight feet tall.
After a while I encountered a path which entered the balsam
thicket, and I assumed that it marked an entrance to a detour around the mud. I
followed the path – and after a while realised that it was going downhill and
was not a detour. Eventually, I came to the river bank and concluded that the
path had probably been made by fishermen. I turned around and then realised that
the boots that I was wearing had little traction on the slippery, muddy, upward
slope that I was trying to negotiate. I fell over a couple times and generally
floundered around in the midst of this tall, impenetrable balsam thicket. After
a while I began to imagine the headline: “Body of Chorlton man found on river
bank at Urmston.”
Somehow, though, I survived, and eventually emerged wiser,
sweatier and a lot muddier.
Dave Bishop, July 2012
References:
Beerling, David J. and Perrins, J.M., ‘Impatiens glandulifera
ROYCE (Impatiens Roylei Walp.)’, Journal of Ecology, 81, 367 – 382, 1993.
Grindon, Leo H., ‘The Manchester Flora’, William White,
1859.
Robinson, William, ‘The English Flower Garden’, Hamlyn ed.
1984 (first pub. 1883)
Rotherham, Ian D., ‘Himalayan Balsam – the human touch’,
paper presented to the Institute of Ecology and Environmental Management
Conference, Birmingham, 2000
Smythe, F.S., ‘The Valley of Flowers’ Cadogan Books ed. 1985
(first pub. 1938)
Stace,
Clive, ‘New Flora of the British Isles’, Cambridge University Press, 3rd
ed., 2010
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