The Rural Voice, 2000-08, Page 49Gardening
Hogweed: not a gentle giant
By Rhea Hamilton -Seeger
Have you ever had a delightful
new addition to your garden only to
Lind out that it is a monster?
Two springs ago my father shared
a wonderful new plant with me. He
had the seeds given to him and was
impressed with the size of the leaves
and thought it would make a
wonderful attraction beside our pond.
It has leaves bigger than our rhubarb
and more deeply cut and in the first
year it grew to a wonderful three feet
high. It survived its second winter
here and this spring we were
rewarded with even bigger leaves
plus a towering 10 -foot stalk
supporting umbrellas of white
flowers. Along the edge of our pond
it is quite an attraction.
My husband became more serious
about this plant than I, and
remembered reading a health bulletin
about it. We did some researching.
We have a wonderful specimen of
Heracleum mantegazzianum or for
the rest of us Giant Cow Parsnip or
Giant Hogweed.
It first came to public attention
around Tara along the banks of the
Saugeen in the early 1970s. Several
children had been using its hollow
stems as telescopes and blowpipes
and developed serious weeping
rashes that eventually healed leaving
a skin pigmentation that took several
months to clear away.
It originally hails from the Caucus
region between the Caspian Sea and
Black Sea and is a member of the
parsley family. Its Targe size sets it
apart from smaller look alikes such as
H. maximum Bartram and H.
sphondylium Linnaeus.
Aside from the size there are a few
other distinctive characteristics that
will help you determine if Giant
Hogweed is in your garden or, worse,
in your farm land.
The stem is dark reddish -purple
and the leaf stalks are spotted. If you
look closely at the spots you will see
bristles. These bristles, when broken
off, will ooze a sap that causes an
irritation. The H. maximum has soft
hairs but not the colouring and H.
sphondylium, a rare weed, has long
white hairs on its stems, leaves, and
leaf stalks.
The other difference is in the
seeds. The Giant Hogweed has Targe
elliptical and very full, fat seeds. I
can't tell with ours as we donned
gloves and clipped off the newly
formed seed heads.
When the plant is in active growth
(June and July) it produces copious
amounts of sap. This sap acts like
poison ivy. It will burn the skin
causing a Targe painful, watery blister
which takes a couple of weeks to heal
and leaves a red scar that lasts for
several months. The reaction to the
sap is further stimulated by exposure
to the sun.
If you get juice on your skin
wash immediately with either lots of
water or, better still, with soap and
water and use a skin lotion normally
used to relieve irritations and insect
bites.
But cutting down the plant will not
eliminate it from your garden. It has a
large tuberous rootstock which will
send up a new shoot each spring. In
test gardens it was discovered that the
plants will die down once they have
set seed or after four years. But they
produce thousands of winged seed
that are either blown about,
distributed by birds or spread by
streams and rivers (the seeds will
float for three days). While it prefers
wet areas it does well in your back
yard.
We have had our discussion about
this enormous beauty in our yard, for
its size and majesty in the garden
cannot be denied. For the time being
we are keeping a close eye on it.
Since it is in the back of the pond
garden where no one goes it has had a
reprieve but we have nipped the seed
heads to prevent it from spreading:
Now we have to see how far it will
spread by root and hope that it is
manageable.
It just goes to show you that
gardeners have to be responsible as
well as knowledgeable and artistic.0
Rhea Hamilton -Seeger and her
husband raise two children at their
home near Auburn. She is a skilled
cook and gardener.
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AUGUST 2000 45