Hemlock (Conium maculatum) is a biennial plant that grows in damp areas and also on drier rough grassland, roadsides, and disturbed ground. It is the plant everyone worries about picking. Hemlock looks very similar to Cow Parsley, Rough Chervil and Sweet Cicely. Close inspection of the stems shows they are different. The plant is tall. It can grow up to 2 metres high.