The bulb, foliage, and seeds of the fennel plant are widely used in many of the culinary traditions of the world. The small flowers of wild fennel (mistakenly known in America as fennel “pollen” ) are the most potent form of fennel, but also the most expensive.Dried fennel seed is an aromatic, anise-flavoured spice, brown or green in colour when fresh, slowly turning a dull grey as the seed ages. For cooking, green seeds are optimal. The leaves are delicately flavoured and similar in shape to those of dill. The bulb is a crisp vegetable that can be sautéed, stewed, braised, grilled, or eaten raw. They are used for garnishes and to add flavor to salads. They are also added to sauces and served with pudding. The leaves used in soups and fish sauce and sometimes eaten raw as salad.

Fennel seeds are sometimes confused with those of anise, which are similar in taste and appearance, though smaller. Fennel is also used as a flavouring in some natural toothpastes. The seeds are used in cookery and sweet desserts.

Many cultures in India, Pakistan, Afghanistan, Iran and the Middle East use fennel seed in their cookery. It is one of the most important spices in Kashmiri Pandit and Gujarati cooking. It is an essential ingredient of the Assamese/Bengali/Oriya spice mixture panch phoron and in Chinese five-spice powders. In many parts of India and Pakistan, roasted fennel seeds are consumed as mukhwas, an after-meal digestive and breath freshener. Fennel leaves are used as leafy green vegetables either by themselves or mixed with other vegetables, cooked to be served and consumed as part of a meal, in some parts of India. In Syria and Lebanon, it is used to make a special kind of egg omelette (along with onions, and flour) called ijjeh.

Many egg, fish, and other dishes employ fresh or dried fennel leaves. Florence fennel is a key ingredient in some Italian and German salads, often tossed with chicory and avocado, or it can be braised and served as a warm side dish. It may be blanched or marinated, or cooked in risotto.

In Spain the stems of the fennel plant are used in the preparation of pickled eggplants, “berenjenas de Almagro”.

Medicinal uses

Fennel (Foeniculum vulgare) essential oil in clear glass vial

Fennel contains anethole, which can explain some of its medical effects: It, or its polymers, act as phytoestrogens.

The essence of fennel can be used as a safe and effective herbal drug for primary dysmenorrhea, but could have lower potency than mefenamic acid at the current study level.

Intestinal tract

Fennel is widely employed as a carminative, both in humans and in veterinary medicine (e.g., dogs), to treat flatulence by encouraging the expulsion of intestinal gas. Anethole is responsible for the carminative action.

Mrs. Eencher Herbal states:

On account of its carminative properties, fennel is chiefly used medicinally with purgatives to allay their side effects, and for this purpose forms one of the ingredients of the well-known compound liquorice powder. Fennel water has properties similar to those of anise and dill water: mixed with sodium bicarbonate and syrup, these waters constitute the domestic ‘gripe water‘ used to correct the flatulence of infants. Volatile oil of fennel has these properties in concentration. Commercial preparations of fennel  are widely available as alternative treatment for baby colic. Fennel tea, also employed as a carminative, is made by pouring boiling water on a teaspoonful of bruised fennel seeds.

Fennel can be made into a syrup to treat babies with colic (formerly thought to be due to digestive upset), but long-term ingestion of fennel preparations by babies is a known cause of thelarche.

Eyes

In the Indian subcontinent, fennel seeds are also eaten raw, sometimes with some sweetener, as they are said to improve eyesight. Ancient Romans regarded fennel as the herb of sight.Root extracts were often used in tonics to clear cloudy eyes. Extracts of fennel seed have been shown in animal studies to have a potential use in the treatment of glaucoma.

Blood and urine

Fennel may be an effective diuretic and a potential drug for treatment of hypertension.

Breastmilk

There are historical anecdotes that fennel is a galactagogue,improving the milk supply of a breastfeeding mother. This use, although not supported by direct evidence, is sometimes justified by the fact that fennel is a source of phytoestrogens, which promote growth of breast tissue. However, normal lactation does not involve growth of breast tissue. A single case report of fennel tea ingested by a breastfeeding mother resulted in neurotoxicity for the newborn child.

Other uses

Syrup prepared from fennel juice was formerly given for chronic coughs. It is one of the plants which is said to be disliked by fleas, and powdered fennel has the effect of driving away fleas from kennels and stables.