Used plant part
Fruits. Other than most of their relatives, they retain a green colour after drying. As a rule of thumb, a bright green colour indicates a good quality.
The leaves and stalks are occasionally eaten as a vegetable.
Apiaceae (parsley family).
Sweet and aromatic, similar to anis. For other sweet spices, see licorice.
Sterile fennel plant, reddish-brown cultivar ("Bronze fennel")
The contents of essential varies strongly (0.6 to 6%); fruits in the center of a umbel are generally greater, more green and stronger in fragrance. Time of harvest and climate are also important.
The essential oil of the most important fennel variety (var. dulce) contains anethol (50 to 80%), limonene (5%), fenchone (5%), estragol (methyl-chavicol), safrol, alpha-pinene (0.5%), camphene, beta-pinene, beta-myrcene and p-cymen. In contrast, the uncultivated form (var. vulgare) contains often more essential oil, but since it is characterized by the bitter fenchone (12 to 22%), it is of little value.
Note In large parts of Asia, fennel and anis given the same name (see below).
The genus name foeniculum (Latin for "little hay") probably refers to the aroma of fennel and is the source of the name of fennel in many contemporary European languages.
In the Hindi tongue, anis and fennel are often synonymously caalled saunf, although only fennel is a traditional spice of the region. To make a clear distiction between the both, fennel may also be called moti saunf "thick fennel", because its fruits are somewhat larger.
The Indonesian name jintan manis "sweet cumin" (also applied to anis) reflects the much greater importance of cumin, of which fennel is thought to be a variety, in Indonesian cuisine. Analogous formations are French aneth doux or Russian sladkiy ukrop "sweet dill". All these spices (anis, cumin, dill and also caraway) belong to the same plant family (Apiaceae) and, in varying degree, resemble each other in shape and fragrance.