Fennel is one of the most commonly used herbs in Ayurveda. This is partly due to the fact that it is one of the best spices for the high-pitta physiology. It is also due to the fact that it is estrogenic and helpful in balancing female hormones.
The name for fennel in Sanskrit is shatapushpa (hundred flowers). It also goes by chatra (umbrella shaped) and atilambi (very skinny and tall).
Fennel is katu (pungent), ushna (warming), tikshna (sharp), laghu (light) and dipani (stimulating digestion). These properties are held in common between almost all spices—it is necessary for spices to be hot to stimulate digestion. But fennel is also madhura (sweet). You can taste the sweetness of fennel when you chew it. This is the soma in fennel which balances its heating qualities. Because fennel has a bit of soma (cooling vibration) to balance the agni (heating vibration) and marut (moving, intelligent vibration) of the spice, it is less likely to create problems in people with high pitta.Nevertheless, in extremely high pitta people, it can cause problems. Also, if it is used in large quantities, it can create a pitta imbalance in anyone.
Fennel is a cooling spice, contributing mainly the sweet taste with an undertone of the bitter taste..According to Ayurveda, fennel is extremely good for digestion. It acts as a general toner for the digestive system, and is particularly good for enhancing Agni, the digestive fire, without aggravating Pitta. In India, eating a few toasted fennel seeds after a meal is a common practice, both to aid digestion and to freshen the breath.
Fennel seeds can be used whole or ground. Whole fennel seeds, sautéed in Ghee, contribute aroma and flavor to dry vegetable dishes, and ground fennel works very well in sauces. Fennel combines well with other ayurvedic spices such as cumin, coriander, dried ginger and black pepper. Fennel seeds can be baked into cookies and muffins and a small quantity of ground fennel can be added to rice pudding for an exotic flavor
Reference –
http://www.vaidyamishra.com/products/Fennel-%252d-Learn-About-A-Great-Spice-For-High-Pitta-Low-Agni.html
http://www.mapi.com/ayurveda_health_care/recipes/spicefennel.html