Hemlock, Carrot Fern (Conium maculatum). Hemlock, is a highly poisonous biennial herbaceous flowering plant in the carrot family Apiaceae, native to Europe and North Africa. All parts of the plant are toxic, especially the seeds and roots, and especially when ingested. Poison hemlock contains coniine and some similar poisonous alkaloids, and is poisonous to all mammals (and many other organisms) that eat it. In classical times it was given to condemned prisoners, especially those in high positions. Conium maculatum is the plant that killed Theramenes, Socrates and Phocion. Cofiorito, DSibillini, Umbria, June 2017