By John Francis, Bruce Peninsula Press
Wild Parsnip has been spreading along roadsides in MNBP for more than a decade. The heaviest infestation is along Highway 6 between Lindsay Road 5 and Ira Lake Road. In much of that stretch of highway, it forms a dense band along both sides of the road.
Wild parsnip (pastinaca sativa) is the wild plant from which the edible parsnip was derived. The wild species originated in Eurasia; as a crop it is grown round the world. Farmers know to handle the leaves and shoots carefully, to avoid contact with the sap. As the wild plant spreads along roadsides, the general public needs to learn how to live with Wild Parsnip.
The toxin involved is a furanocoumarin — a class of photochemicals that cause skin to blister when exposed to sunlight. Furanocoumarins are not actually poisonous — they just make your skin incredibly light-sensitive. The plant can be handled quite safely in subdued light. If you find yourself with a painful, blistering rash (and you haven’t been around poison ivy…) you should cover the affected area to shield it from light, then wash the area with soap and warm water. (Once you have washed off the furanocoumarin oil, the blistering should stop.)
The most dangerous activity in parsnip infestations, is weed-whacking while scantily clad. Cutting and removing Wild Parsnip should be done in subdued lighting, while fully dressed.
The root of Wild Parsnip is quite edible, resembling a scrawny, grey-white carrot. (The cultivars used in farms and gardens produce a much more impressive root.)
The Wild Parsnip invasion is thought to have started at the parking lot of Lindsay Tract Trails. Once it reached the roadside, it was spread quickly by the tractor that cuts the roadside weeds. You can see that the Ministry has (finally) learned this lesson — the weed-cutter avoided all the Wild Parsnip infestations this year, which will limit the spread. (You can see this as you drive down the highway.)
Wild Parsnip is a biennial — it puts up a rosette of leaves the first year, then a tall flowering stalk the second year. (It may sometimes continue to flower for a few years after that.) The flower heads are flattish-topped umbels, similar to Queen Anne’s Lace. The leaves look much like Italian Parsley, but larger. The first year rosette of leaves may be 30cm wide; the second-year flower stalk may be 50 to 170cm high (two to five feet).
A couple of times over the last ten years, the Ministry has sprayed the Wild Parsnip infestations with herbicides. This has knocked it down for the rest of the year, but it would probably need to be done year after year to eliminate the infestation. Wikipedia states that glyphosate (aka Round-up) is effective against Wild Parsnip.
Two close relatives of Wild Parsnip — Cow Parsnip and Giant Hogweed — are also found in MNBP. Both contain furanocoumarins and require the same caution as Wild Parsnip. Fortunately, they are much less common. Cow Parsnip is similar to Wild Parsnip but has white flowers. Giant Hogweed is very similar in shape but is simply huge. They are often 4-6 metres tall with parsley-shaped leaves the size of newspaper pages and white flower heads the size of pizzas.
