Weed Phobia and the War on Nature
Weed phobia is rampant in the countryside. The latest target -- the weed du jour' -- is the so-called wild parsnip' or poison parsnip'. The Eastern Ontario Health Unit put out a warning in June identifying it as a health risk and encouraging people to remove it from their property. Some people I know have been out spraying it illegally. Now two Ottawa councillors want the city to use herbicides to eliminate it from public property.
I am not concerned about people cutting it down. It is hardly an endangered species -- it's an invasive exotic. I am concerned, however, about eliminating all the other plants that grow around it. And it would be utter folly to use pesticides against it, exposing the public to truly lethal poisons (which pesticides are by definition) in order to kill a plant that is harmless to most of us. The best thing would be to eat it -- and some do!
I have been wandering through clumps of wild parsnip for years on my walks through the countryside and I have never had a problem. I was surprised by all the fuss. I went out and broke off some stems and rubbed the ends on the skin of my arms. As I suspected, nothing happened. So I decided to do a little research. It looks as if I may be the only one who bothered!
What we are dealing with here is just your ordinary, garden-variety parsnip, pastinaca sativa, the same stuff my mother used to make me eat when I was a kid, telling me how nutritious it was. Strictly speaking, it's not wild'. It's naturalized'. Many of our common roadside plants are naturalized domestics; that's because the native plants are mostly woodland species and don't do well in direct sunlight. Removing the naturalized plants just invites more infestations.
Parsnip is a member of the Apiaceae or carrot family, which also includes anise, caraway, celery, chervil, coriander, cumin, dill, fennel, lovage and parsley. Members of the carrot family have a chemical called furanocoumarin in their sap which can cause a chemical burn on the skin when exposed to ultraviolet radiation. (The condition is known as photodermatitis, or phytophotodermatitis to be precise).
I say can cause' because not everybody is sensitive to furanocoumarin. Some sources dispute this, but in any case, the effects vary with exposure. The usual result is a slight discoloration of the skin -- like liver spots or freckles. You may not even notice. If you have a heightened sensitivity or are heavily exposed, you may get severe blistering and a persistent scar.
It can be quite nasty and I feel sorry for anyone who has ever gotten a severe furanocoumarin burn. People should be aware of the risk -- but there is no need to panic!
Prevention is simple -- if you are afraid you might be sensitive to it, avoid it as you would a clump of stinging nettle. The cure is pretty straightforward, too -- wash the affected area with water and cover it to protect it from sunlight.
In order to get a severe burn, if would appear that you literally have to work at it. Most published studies involve agricultural workers, who spend long days in the sun picking vegetables. Around here, the few cases I have heard about involve people using weed-whackers (an instrument of that devil, that!) without protective clothing.
How many confirmed cases have there been in Eastern Ontario? Nobody seems to know. Surely even plants have a right to a fair trial before being publicly executed!
Other plants contain furanocoumarin, too -- notably citrus fruits and figs. I read on the Medscape website about a case of someone who got severe blistering after cutting up some limes and then going sunbathing. Anyone for a ban on citrus fruits?
Keep this in mind when you read about parsnip sap causing temporary or permanent blindness if you get it in your eyes. That is scary, for sure. Just remember that the same thing would be true for lemon juice -- and any number of other things. Putting things in your eyes is generally inadvisable.
Keep in mind, too, that there are a lot of poisonous plants out there. Have a look at the lists on the Canadian Poisonous Plants Information System website, or check the more informative and readable Wikipedia entry. Notice that the lists include a lot of common food plants and ornamentals, and even some interior plants. Should we eliminate all of them?
Alarmism about parsnips feeds into the weed phobia' which I notice all around me -- the irrational fear and hatred of natural (or naturalized) vegetation. It is as if any species of plant that you can't buy in a store is automatically a weed and therefore dangerous and must be eradicated. It's like a full-scale war on nature, with no holds barred nor quarter given.
I don't know what is behind this weed phobia. But I can see who benefits -- the people who sell herbicides to kill them. The people who sell riding lawnmowers and weed whackers to cut them down. The people who sell commercial plants and seeds to replace them.
Where are we going if we continue to eliminate wild plants? What happens to the insects and the birds? Are we headed towards ecosystem collapse? Look at what is happening with the bees and the butterflies.
People who live in the country should know better than anybody else that we depend on nature absolutely, for everything. We had better learn to respect it.
* "Wild Parsnip on the Rise in Eastern Ontario", press release: Eastern Ontario Health Unit, June 25, 2013; http://www.eohu.ca/media/view_release_e.php?pressID=183
* "Environmental Health - Dangerous Weeds", Leeds, Grenville & Lanark District Health Unit; http://www.healthunit.org/hazards/dangerousweeds.html
* "Councillors want herbicides sprayed against wild parsnip", CBC News, Jul 24, 2013; http://www.cbc.ca/news/canada/ottawa/story/2013/07/24/ottawa-councillors-want-herbicides-sprayed-against-wild-parsnip.html
* Samuel Thayer, "Wild parsnip: It's like raiding a garden, but better", Countryside & Small Stock Journal; http://www.countrysidemag.com/91-3/samuel_thayer/
* "Botanical Dermatology: Phytophotodermatitis", The Internet Dermatology Society, Inc.; http://telemedicine.org/botanica/bot5.htm - excellent source
* "Phytophotodermatitis", Medscape: http://emedicine.medscape.com/article/1119566-overview)
* L Lutchman, V Inyang, D Hodgkinson (1999). "Phytophotodermatitis associated with parsnip picking". Emergency Medicine Journal 16 (6): 453 -- 4; http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1343418/pdf/jaccidem00033-0059.pdf
* "Introduction - Canadian poisonous plants", Canadian Poisonous Plants Information System; http://www.cbif.gc.ca/pls/pp/ppack.html_doc?p_type=434&p_x=px
* "List of poisonous plants", Wikipedia; http://en.wikipedia.org/wiki/List_of_poisonous_plants
* "11 Common Plants That Can Cause Dangerous Poisonings", Medscape; http://reference.medscape.com/features/slideshow/dangerous-plant-poisonings
Facts about wild' parsnip
* So-called wild' parsnip is not a wild species or variety of parsnip with any distinctive properties of its own. It is simply domestic parsnip (pastinaca sativa) which has become naturalized, like its relative, the unbiquitous wild carrot (also known as Queen Anne's Lace).
* Parsnip is a member of the Apiaceae or carrot family, a large family with more than 3,700 species. Besides carrots and parsnip, the family includes the common food plants anise, caraway, celery, chervil, coriander, cumin, dill, fennel, lovage and parsley.
* Members of the carrot family have a chemical called furanocoumarin in their sap which can cause a chemical burn on the skin when exposed to ultraviolet radiation. The condition is known as photodermatitis, or more precisely as phytophotodermatitis.
* Other plants contain furanocoumarin, too -- notably citrus fruits and figs.
* Not everybody is sensitive to furanocoumarin (disputed)
* Reactions vary with the degree of sensitivity and exposure.
* The usual result is a slight discoloration of the skin -- dark spots similar to liver spots or freckles. They may go completely unnoticed.
* People with heightened sensitivity may get severe blistering and a persistent scar
* Treatment is simple -- wash the affected area with water and cover it to protect it from sunlight.
* Without treatment, blistering may begin about 24 hours after exposure
* Rotary mowers and weed whackers are probably the worst way to control parsnips, as a lot of sap is released at high velocity. Protective clothing is recommended -- goggles, rubber gloves, rubber boots and coveralls
* The roots and seeds are edible and highly nutritious. As the plant is biennial, the root should be harvested in the fall of the first year.
* Bob McDonald