Monday, June 25, 2012

ladybug dancing

lady bug dancing
among the ferny green leaves
of poison hemlock

We've had a proliferation of poison ivy this spring, and now the wild members of the parsley family, Apiaceae, are blooming in profusion along roadsides and creek banks -- wild carrot, wild parsnip, wild chervil and their dangerous cousin, poison hemlock. Contact with poison ivy can cause a skin rash, but poison hemlock contains a neurotoxin that causes paralysis and death when ingested even in small amounts by people or livestock.

Conium maculatum was introduced to North America from Europe and is often mistaken for a garden ornamental. With its ferny leaves and white umbels the plant is attractive, but all parts of it are poisonous -- leaves, stems, roots and seeds. The volatile alkaloids in hemlock have been used as a poison since ancient times. In ancient Greece it was used on condemned prisoners. The most famous case is the death of the philosopher Socrates in 399 BC. The Athenian government condemned him to death or exile for his teaching methods which aroused skepticism and impiety in his students. He chose death by drinking an infusion of hemlock.

I have been seeing lots of plants that appear to be poison hemlock all along the highway, especially near moist areas, and even in town. Today I decide to check to make sure it's poison hemlock I'm seeing and not wild chervil, a close look-alike. I find a group of these tall plants, some twice my height, with clusters of lacy white blossoms and lush foliage, growing on either side of the bridge over our creek. They are rubbing shoulders with their cousins, wild carrot and wild parsnip, as well as wild elderberry. One tall plant is growing right up through the middle of an elderberry shrub. Elderberry flowers are also white and grow in large clusters, but the leaves are pinnate, with many leaflets with serrated margins, and the bark of this deciduous shrub is gray.  

The finely divided, fern-like leaves of poison hemlock resemble wild carrot, but are not as feathery, and they are not hairy like wild chervil. The leaves give off a musty odor when crushed. The hollow stems are smooth, not hairy like wild carrot, but it's the purple splotches on the greenish-yellow stems that distinguish poison hemlock from its parsley cousins. 

I'm surprised to discover a number of ladybugs crawling rapidly all over this poisonous plant. Apparently they are not affected by the toxins, but what's the attraction?

The white flowers are already starting to turn to green seeds. Poison hemlock is a biennial that reproduces solely from seeds. It produces a ferny rosette the first year and tall flowering stems the second year, from May to August, followed by green, ridged seed capsules that turn brown when the seeds mature, much like wild parsnip. 

Jefferson County Noxious Weed Control Board offers a number of recommendations for controlling poison hemlock, which is required county wide. The best method is to pull or dig up small plants when the ground is moist. Wear gloves and don't touch the eyes or mouth after handling the plants. Plant parts may not be safe to leave on site or put into the compost because they decompose slowly, taking several years for the poison to dissipate. Do not burn the plants because the smoke releases toxins into the air. Repeated mowing will weaken the plant and reduce its competitive ability. Some herbicides are effective if applied during the early stages of growth, but do not use herbicides over or near water bodies. They also recommend bagging the seeds. But then what do you do with the bags?

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