The genus of poisonous Mediterranean plants commonly called deadly carrots is Thapsia.
Thapsia is a small genus in the carrot and parsley family, Apiaceae. Its species are concentrated around the western Mediterranean, with the range extending into parts of the Iberian Peninsula, North Africa, and Atlantic-facing regions. They are herbaceous perennials with large umbels of yellow flowers and distinctive winged fruits.
The common name can be misleading: deadly carrots are not ordinary cultivated carrots that have become poisonous. The plants are unrelated at the genus level to Daucus carota, the domestic carrot, although both belong to Apiaceae. Thapsia species contain irritating and toxic compounds, and contact with some roots can cause intense itching and swelling.
Thapsia has a long history in traditional medicine, but historical use does not make the plant safe. Thapsia villosa, the villous deadly carrot, is one notable species and was described by Carl Linnaeus in 1753. It can also be confused with giant fennel, Ferula communis, because the plants share a similar appearance and some regional common names.