There are two Poisonous Hemlocks to look out for in this family
The “Poisonous Hemlocks” Poison Hemlock and Water Hemlock are both very poisonous plants, fairly similar at first glance there are differences between these two plants. Water Hemlock being the most poisonous of the two.
Water Hemlock [also; Hemlock Water Dropwort]
Poison Hemlock [also; Hemlock]
The major differences you will find is in the stems, flowers, and leafs. On the poison hemlock the stem has these purple spots, where as the water hemlock is without.
The flowers of the Water Hemlock are more round in shape versus the flatter, fanned out appearance of the Poison Hemlock. The Poison Hemlock assuming a branching canopy like effect.
The leafs are the final distinguishable difference. The leaf of the Water Hemlock takes a more fern like appearance. Where as that of the Poison Hemlock takes a more straight look.
The “Deadliness Rating” of the Poison Hemlocks is: Slow; Lethal.
The symptoms of the poison show around 15 minutes, and the poison can kill within a few hours with respiratory failure.
All parts of the Hemlocks are poisonous, there is no usage for any part of the plant.