|
|
  |
|---|
One that's important to know is poison hemlock, Conium maculatum. Just this week, while visiting in a friend's garden, I saw a tall specimen of poison hemlock rising right out of a bed of forget-me-nots. She noted that she'd kept it in the garden because, though she didn't know what it was, she thought it was "pretty." This plant was introduced to North America from Europe, and has often been mistaken for a garden ornamental. The plant is attractive, but can be lethal to people and animals.
Poison hemlock is a member of the wild carrot family, and is common along roadsides, waterways, and in cultivated areas. It resembles anise or wild parsley, and is classified in the family Umbelliferae, the parsley family. All parts of this plant are poisonous: leaves, stems, roots, and fruits. Poison hemlock contains volatile alkaloids that have been used as a poison since ancient times. The famous incident of Socrates' death in Athens in 329 BC occurred when he was given the juice of poison hemlock to drink.
How can you identify it? Look closely at the stem of any plant you may suspect of being poison hemlock. The stem is hollow, smooth (not hairy) and marked with purple streaks and blotches. These blotches and streaks on a green hollow hairless stem, and the mottled purple spots, are definite identifiers of the plant. The finely divided leaves, fern-like, resemble Queen Anne's lace. Flowers are lacy and white, appearing from late May to August.
Poison hemlock is a biennial. It grows from seeds. During the first year, it produces a rosette of fern-like leaves close to the ground. The second season it bolts to form the tall, erect, flowering stems which can be from 4 to 8 feet tall. The white flowers develop into green, ridged seed capsules which turn brown when the seeds mature. The leaves and flowers smell distinctive, a "mousey" odor.
Poison hemlock must be removed. Do not allow this weed to go to seed. Wear gloves when handling it. Don't put it into the compost. Dead stalks can remain poisonous for two or three seasons. Don't incinerate it (don't inhale the smoke). The herbicide 2,4-D applied to the early stages of growth will kill it.
If you need more help identifying this or other weeds, contact your local Noxious Weed Control Board. They will help with photos and information about getting rid of the weed. In King County call 253-872-2972. In Pierce County, call 253-798-7263.
A color photo of purple blotching on the stem of poison hemlock can be seen at http://www.oneplan.state.id.us/pest/nw21.htm
Hortsense: Managing plant problems with Integrated Pest Management
