Fennel is a flowering plant species in the carrot family. It is a hardy, perennial herb with yellow flowers and feathery leaves. It is a highly flavorful herb used in cooking and, along with the similar-tasting anise, is one of the primary ingredients of absinthe. Dried fennel fruit is an aromatic, anise-flavored spice, brown or green in color when fresh, slowly turning a dull grey as the fruit ages.