1. Check the Stem
Poison hemlock features a very straight, erect stem with easily identified ridges along the surface. The stems are hollow inside--except at those points where the leaves attach--and feature purple spots near the base of the poison hemlock. They grow anywhere between 3 and 6 feet tall.
2. Location, Location, Location
Poison hemlock is more prevalent in the American West and Mountain West regions, such as California, Oregon, Colorado and Montana. It can also be found in parts of Europe, Asia and Australia. It thrives in lower elevations and it needs a lot of water to grow, so it will appear near streams, flood plains, culvert ditches and standing water in areas that see a decent amount of rain.
3. Look for Patterns
Poison hemlock leaves are shiny and green with a triangular shape that closely resembles parsley (the plant is actually a member of the parsley family). They alternate on either side of each stem, and number between six and twelve on each stem. Each individual leaflet is between 1/8 and 1/4 of an inch long.
4. Stop and Smell the Flowers (Or Not!)
Poison hemlock flowers bloom in mid-summer, usually around July or August. The flowers themselves will be small and white, growing in umbrella-like bunches clustered around a common stalk. They lack any green petals at their base.
5. Make No Mistake! That Ain't No Carrot!
People take poison hemlock most often because they mistake it for wild parsnips or wild carrot. Its root is fleshy and white like those other plants. The key feature is that there are no hairs on the leaves and stem of the poison hemlock. Check the rest of the plant carefully before you attempt to eat the root and leave it for the local fauna if you have any doubts.
