Extremely toxic water hemlock plant found near White Rock Lake

DALLAS (CBSDFW.COM) — An extremely toxic plant has been discovered growing around White Rock Lake, and Dallas officials are taking action to keep park patrons safe.

Dallas Park Maintenance & Operations officials said that several populations of water hemlock were discovered growing around the lake and that after surveying the area, determined that parkgoers were at a substantial risk of coming into contact with the highly poisonous plant.

Water hemlock looks fairly inconspicuous. It grows between about one-and-a-half to three feet tall and prefers wet areas. Despite their similar names, water hemlock is actually only distantly related to poison hemlock. 

Its closest relatives are actually carrots, parsley, and celery, which it can be sometimes confused for. Like its edible relatives, water hemlock has small, bunched white flowers and medium-sized but broad leaves.

And while carrots, parsley, and celery vital nutrients, water hemlock has high concentrations of a toxin that causes violent convulsions and even death.

The chemical responsible for water hemlock's deadly profile is called cicutoxin. The poisonous compound essentially works in the opposite way that the common anti-seizure medication phenobarbital does, causing the nervous system to become too excited and overactive.

The result is that the brain becomes so stimulated that victims become panicked, have convulsive seizures, and sometimes die. It's so powerful that ingesting even a tiny part of the plant could cause a reaction within 10 minutes.

Officials note that the primary risk of cicutoxin poisoning is through ingestion, but even mere skin contact with the plant could have cause a reaction. 

In fact, water hemlock presents such a high risk to city employees that physical removal is not an option. Instead, the city plans to an herbicide called glyphosate, or Rodeo. It's approved for use near aquatic environments, but Dallas has not used it near White Rock Lake in years. However, they said it's the product that will most effectively kill the entire plant, including the roots.

Dallas PMO plans to begin applying the herbicide on Friday, July 22. They'll monitor it for weeks to make sure it kills the plant and dries up its roots, neutralizing the threat.

Until then, officials said to be vigilant and keep an eye out for the plant. If you spot water hemlock, don't attempt to remove it yourself. Avoid the plant and report your observations to Dallas PMO.