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Water hemlock

By: Garden Gate staff
At a glance, the foliage resembles the herbs chervil, coriander and parsley.

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Water hemlock Cicuta maculata

IDENTIFICATION – At a glance, the foliage resembles the herbs chervil, coriander and parsley. The best way to identify water hemlock is by the purple or red spots near the base of the hollow main stem. Unfortunately, these spots often don’t appear until the plant is mature. In summer, water hemlock blooms with lacy clusters of white flowers atop the 2- to 5-ft.-tall stems.

This is a highly poisonous perennial weed that’s found from eastern Canada to as far west and south as New Mexico. All parts of water hemlock are poisonous. It can be fatal if even a small part of the stout taproot, which looks like a sweet potato or parsnip, is eaten. So be sure to wear gloves when you weed, and wash your hands after handling it. One-year-old plants have a single taproot while older plants have clusters.

FAVORITE CONDITIONS – As you might guess from the name, this is mainly a water plant, found near ponds, streams and irrigation ditches. It doesn’t show up in tilled gardens very often, but it can if the area is damp and rarely cultivated. And you’ll find it in both sunny and shaded areas.

CONTROL – Wearing gloves, pull or dig out water hemlock as soon as you spot it. If you’re not able to remove it by digging, cut the flowering stems off near the ground to prevent seeds. Systemic herbicides, such as Roundup™, are also effective. Apply the herbicide to the low rosette of leaves before the flowering stem stretches in summer.

Published: Oct. 30, 2007
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