Attack of the cow parsnips - the furanocoumarin wars

July 27, 2007

The Dirt Divas

“What on earth happened to you!?” generally isn't what you like to have folks exclaim when they run into you at the grocery store - Especially when they reach for your neck at the same time.

Makes me want to duck behind the potato chip aisle and grab the nearest mirror. Well, at least it wasn't the usual “You look tired, dear,” a lazy quip given my usual appearance after a hard day's work.  

On checking my reflection, I did see some rather alarming red patches looking like a child's strawberry jam-sticky fingerprints on my neck. They weren't particularly sore, so I ignored them thinking they were some kind of bug bite. By the next morning they were larger, darker and beginning to burn. I realized then that my immunity to cow parsnips had finally run out. This was only going to get worse as the weather gal noted a week's worth of sunny summer days ahead.

Cow parsnip is a formidable adversary for anyone lucky enough to be out hiking in the woods on a summer's day. Appropriately named after Hercules, Heracleum sphondylium is a vigorous umbellifer with family in both the old world and the new. As it's common name suggests, it is related to parsnip, as well as parsley, angelica, fennel, dill, coriander, celery, carrot, anise and poison hemlock.

There's something about this umbellifer family that gives it quite an edge in the plant world - furanocoumarin, a potent photo-toxic chemical that scientists think the plants use to protect themselves from fungus attacks and possibly from insect predadation. For humans, these lovely, white flowering behemoths, often mistakenly called Queen Anne's lace (another lovely family member), can deliver a nasty rash that can cause scarring and permanent sun sensitivity to the affected area. Dermatitis from handling vegetables and herbs from this family is common among farm and food processing workers.

Great. The sun's ultra violet rays not only wrinkle us up like prunes and cause skin cancer; they activate the cow parsnip juice and create a nasty rash as well. Heat and sweat intensify the photo-toxic response as does repeated sun exposure. Contact with cow parsnips is practically unavoidable in the woods, so wear clothes that cover your arms and legs. A thick pair of gloves wouldn't hurt.

That's what I was wearing. I got it in the neck. Literally. If I'd noticed it right away I could have washed the area with soap and water and applied a good sunscreen to the area. Once afflicted, your only hope is a hydrocortisone cream or 1 percent triamcinolone cream along with sunscreen and trying not to expose the area to the sun.

It takes less than 15 minutes of sun to start the chemical explosion that results in a rash. It can take weeks to get rid of the awful discoloration it causes.

It is nature's joke that many of the plants that cause human suffering are also the source of many wondrous medical treatments. Furanocoumarin, the light-sensitive chemical of the cow parsnip that causes the skin rash, is being investigated as a way to target and treat certain cancers and is used in the treatment of psoriasis and related skin disorders.

With the use of lasers activating the light or photosensitive properties of this cow parsnip juice, researchers hope to deliver a death blow directly into the cells of some cancers.  The ancient Egyptians adopted the photo-toxic properties of Ammi majus, false bishop's weed, a lovely annual relative of cow parsnips, to restore the skin pigment lost after a bout with vertiglio. The plant juices were rubbed on the affected whitened areas of skin and the patients directed to their beach towels for a bit of tanning or hyperpigmentation - the dark discoloration caused by exposing the plant juices to sun light. In the 1940s, prof. Abdel Monem El Mofty of the Cairo University Medical School developed the modern field of photochemotherapy using furanocuomarin as a regular treatment for psoriasis.

Cow parsnips are nose deep this time of year, so, bundle up and don't forget to wear your mittens, er, gloves.  

Brooke Heppinstall, artist and gardener, is the owner of Wool Wood Studio & Gardens, an art studio and nursery specializing in Alaska-grown perennials and shrubs. Visit online at www.woolwood.blogspot.com.