Fennel is a perennial, pleasant-smelling herb with yellow flowers. It is native to the Mediterranean, but is now found throughout the world. Dried fennel seeds are often used in cooking as an anise-flavored spice.But don’t confuse fennel with anise; though they look and taste similar, they are not the same. Fennel’s dried ripe seeds and oil are used to make medicine.Fennel is used for various digestive problems including heartburn, intestinal gas, bloating, loss of appetite, and colic in infants.t is native to the Mediterranean, but is now found throughout the world. Dried fennel seeds are often used in cooking as an anise-flavored spice. But don’t confuse fennel with anise; though they look and taste similar, they are not the same.