Hemlock

Several plants are called hemlock.

• Poison hemlock is a common European plant, Conium[?] maculatum, family Apiaceae (formerly Umbelliferae); it is toxic, containing the alkaloid Coniine[?].
• Water hemlock is Cicuta[?] virosa, another deadly plant in the Parsley family.

It isn't sure which of above two toxic hemlocks the Greek philosopher Socrates was executed with.

Quite different from these is

• Western hemlock, Tsuga[?] heterophylla. This is a North American coniferous tree, particularly common in the Pacific Northwest.