Florence fennel plants grow between 4 and 10 feet tall. They have a thick underground taproot that looks like a carrot, topped by a fleshy, edible bulb-like structure. Long, fleshy stems grow from the main stalk, topped by feathery green foliage. Fennel plants produce flat-topped clusters of yellow blossoms on tall flowering stems. The fennel plant has a sweet licorice- or anise-like fragrance.
Several other fennel varieties are cultivated in addition to Florence fennel. The sweet fennel plant, Foeniculum vulgare var. dulce, grows around 6 feet tall; its seeds are useful for flavoring candies and liqueurs. The Foeniculum piperitum variety yields Sicilian fennel oil. Florence fennel is available in a number of cultivars, including Purpureum, Bronze and Carosella.
Florence fennel is usually grown as an annual. It prefers full sunlight and cool weather. Fennel plants grown from seed are usually ready to harvest 80 to 100 days after germination. Their leaves and bulbs are useful in salads, soups and sauces. Flavor sausage dishes with fennel seeds, and add the leaves to fish and vegetable dishes.