Pliny the Elder, the legendary Roman scientist and scholar, promoted fennel’s medicinal properties and recommended approximately two-dozen remedies using fennel. By medieval times, fennel was not only used as a curative, but was coveted for a believed ability to protect against witchcraft and evil spirits.

Today, we know that fennel offers a number of phytonutrients that promote antioxidant activity in the body (the source of it’s anti-inflammatory effects). It is a source of manganese, calcium, magnesium, iron and fiber, all of which are important for libido and longevity. The vitamin C found in fennel bulbs is shown to be antimicrobial and is not only useful for it’s anti-aging properties, but may also be useful in boosting the immune system.

  The variety of fennel most commonly used in cooking is called Florence fennel. The plant’s feathery fronds resemble dill and are used similarly as a seasoning in Mediterranean dishes. The stalks are fibrous like celery and make an excellent seasoning for soups and stocks. The bulb, which contains the most nutrients, can be thinly sliced and served raw, sautéed, grilled or roasted.
 
But it is as a spice that we are most familiar with the flavor of fennel. The vegetable’s seeds are a prominent flavoring in Italian sausage, Mediterranean stews and even, occasionally, in artisan breads. Ground into a powder, fennel seeds are also a key ingredient in complex, Indian spice mixes and in Chinese five-spice powder. 
 
A hot trend in recent years is fennel pollen. It is collected from the flowers of wild fennel, dried and sold in tins through gourmet retailers. Rub it on fish before grilling, finish a pasta dish or dust a salad with this subtle, anise-like flavoring.

Additional Sources:
The World's Healthiest Foods http://www.whfoods.com/genpage.php?tname=foodspice&dbid=23
 
Howard Yoon. "Kitchen Window: don't forget the fennel." NPR.com
http://www.npr.org/templates/story/story.php?storyId=6710330
 
Michael Albertson. Temptations. Fireside, 2002.