For Giant fennel (Ferula communis) see Ferula.

Fennel (Foeniculum vulgare) is a species in the genus Foeniculum (treated as the sole species by many botanists), and is native to southern Europe (especially the Mediterranean) and southwestern Asia. It is a member of the family Apiaceae (formerly the Umbelliferae).

It is a highly aromatic perennial herb, erect, glaucous green, and grows to 2 m tall. The leaves grow up to 40 cm long; they are finely dissected, with the ultimate segments filiform, about 0.5 mm wide. The flowers are produced in terminal compound umbels 5—15 cm wide, each umbel section with 20—50 tiny yellow flowers on short pedicels. The fruit is a dry seed from 4—9 mm long, half as wide or less, and grooved.