Common Fennel (Foeniculum Vulgare) is a perennial herb in the Parsley family and an important foodplant for many papilio species. We grow plants each year to feed our larvae of the Black Swallowtail (Papilio polyxenes / asterias) and the British and European Swallowtails (Papilio machaon ssp.) Common fennel prefers full sun, and light, well drained good garden soil. Eventual height 3-5 feet tall.