|Mammoth Fennel produces extra-large sized bulbs. Perennial producing airy clumps of very fine, triangular, anise-flavored leaves. Slender arching branches produce compound umbels of tiny yellow flowers, followed by seeds. Fennel has a licorice-like flavor. The seeds, leaves, and roots are all widely used. Don't plant near dill, they will cross pollinate. Great in a variety of stews, especially bouillabaisse.