Be careful! There is an alien species in the road ditches and the idle fields around Perry that might cause you harm. It is a poisonous plant called wild parsnip. Sometimes it is called wild dill.
Its scientific name is Pastinaca sativa, and it is in the carrot family. The sap of this plant contains a chemical called psoralen. When it gets on a person’s skin, it causes a painful condition called photo-dermatitis. The sap of the plant reacts with sunlight and causes a rash.
I first heard about this plant 20 years ago when I was working at the Neal Smith Prairie Learning Center east of Des Moines. I knew about poison oak and poison sumac< and I had several bouts with poison ivy, but this poisonous plant was new to me. I didn’t think it would affect me.
A few days later, I had long streaks of a reddish-brown rash on my forearms that soon developed into painful blisters. It felt like a bad sunburn. It took a few weeks for the condition to go away. Some people have reported scars from the blistering that have lingered on for two years.
There have also been reported cases of dogs getting this type of reaction from the plant’s sap.
People working around these plants should wear long sleeves, long pants, gloves and eye protection. If the sap gets on exposed skin, it must be washed off with soap within 10 minutes, or the rash will develop.
This is the time of year when the plant is in full bloom, and it will continue to bloom until mid August. I have seen scattered patches of wild parsnip around Perry. There is a lot of it growing at the corner of U.S. Highway 169 and Iowa Highway 141, for instance.
It is from two to five feet tall and has umbrella-shaped flower heads made up of many tiny yellow flowers. The flattened tops of the flowers are two to six inches across. The leaves of the plant are similar to leaves of celery but they have a saw-tooth edge.
Wild parsnip is a biannual plant. In its first year of growth, its leaves form a rosette pattern very close to the ground. The second year is when it becomes the tall, weedy-looking plant that is currently seen along the roadsides.
There are other common plants that have a similar appearance and could be confused with wild parsnip, including Queen Anne’s lace, wild carrot, poison hemlock, cow parsnip and giant hog weed. All of these are in the carrot family and are reported to contain the poison chemical psoralen in varying amounts.
The earliest written record about wild parsnip is dated to 1884 in Wisconsin. Now the plant has spread all across the Midwest and into central Canada. It was brought to North America by European settlers probably for a garden vegetable.
Parsnip roots were a favorite food of the Greeks and Romans, and people in Ireland use the root of the plant to make beer, boiling it in water with hops. The parsnip roots sold in produce section of grocery stores is a cultivar of wild parsnip.
Some states have declared this plant a noxious weed, but Iowa has not. Besides being harmful to humans, the plant is spreading, and as it does it chokes out native plants. It does have some good uses. It plays a minor role in the food chain, and it is a favorite food of the black swallowtail butterfly’s larva, and some flies like the flowers nectar.
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