A: It could have easily been elderberry but after looking over the site and sending photographs to the University of Florida, we determined the plant to most likely be a water hemlock. Water hemlock, Cicuta maculata, is the most violently toxic plant growing naturally in North America. Only a small amount of the toxic substance in the plant is needed to produce poisoning in livestock or in humans. The toxin cicutoxin, acts directly on the central nervous system causing convulsions.
Cicutoxin has a strong carrot-like aroma. Water hemlock has small, white flowers that grow in umbrella like clusters which looks very similar to the flower of the wild carrot, elderberry and poison hemlock. However, there are some very distinct differences which make the identification easier. Queen Anne’s lace and poison hemlock have very convoluted or lobed compound leaves called tri-pinnate. The leaves of water hemlock and elderberry are more similar to each other but without the deep lobes. Water hemlock stems are herbaceous and smooth (no hair) whereas Elderberry stems are woody (more like a shrub). Queen Anne’s lace has green, hairy stems whereas poison hemlock has smooth, purple spotted stems.
In cases of any type of plant poisoning in humans, contact a poison Florida control center (open 24 hours a day) at 1-800-222-1222 as quickly as possible. All parts of the plant are poisonous but the root is especially potent. The green seed heads have caused death losses in cattle. The leaves and the stems lose their toxicity as they mature. Good reason to not eat something unless you are absolutely certain of the identification.
Since I have said all this scary stuff, I know there will be some concerns about water hemlock growing in a conservation area but there is no reason to become overzealous to remove these plants. If we start removing poisonous plants (azaleas, lantana, coral bean, oleander, etc.), where will it end? All types of poisonous plants have been around for thousands of years and very seldom cause any harm. As a reminder – we should respect all plants and their potential power to both help and harm. However, people who have livestock and a water source should be vigilant to ensure poisonous plants are not growing on their property where animals could ingest them accidentally.