Fennel
Also known as Foeniculum vulgare, fennel seed, wild fennel, finocchio, finocchietto, Fenchel, fenouil, hinojo
The signature spice of central and southern Italian sausage, and the reason finocchiona is called finocchiona. Its anise character comes from the same compound as star anise and aniseed, which is why the three are sometimes swapped and should not be.
Fennel seed is the dried fruit of Foeniculum vulgare, another umbellifer alongside coriander, cumin and caraway. Its aroma is dominated by anethole, sweet and aniseed-like, with a warm background that is softer and less medicinal than star anise.
In charcuterie it is Italian above all. Finocchiona, the Tuscan salami, is named after it, and the story that Tuscan makers used wild fennel to mask or stretch expensive black pepper is repeated so widely that it should be treated as tradition rather than documented fact. It runs through the southern Italian fresh sausages, the salsiccia of Naples and Calabria, the Sicilian preparations, and it is the defining seasoning of Italian-American sweet and hot sausage. It appears in Spanish and Portuguese work, in the Indian and Middle Eastern sausages, and in the Chinese five-spice blend that seasons some cured meats.
Two forms are used and they are not the same. Cultivated fennel seed is plump, pale green-brown and relatively mild. Wild fennel, finocchietto, is smaller, darker and considerably more intense, and where an Italian recipe specifies selvatico it means the wild seed and is asking for that intensity. Fennel pollen, harvested from the flower heads, is more concentrated still and is used at a fraction of the weight.
Whole and ground behave differently in a familiar way. Whole seed gives bursts of flavour when bitten, which is the classic effect in a coarse salsiccia, and it survives long fermentation and drying well. Ground fennel distributes evenly and is markedly more assertive at the same weight. A recipe specifying whole seed and receiving ground will read as over-spiced.
The confusion to avoid is with aniseed and star anise. All three carry anethole, so they smell related, but aniseed, Pimpinella anisum, is sharper and purely sweet, and star anise, Illicium verum, is a different plant family altogether and is far more powerful and slightly liquorice-medicinal. Substituting star anise for fennel by weight will overwhelm a sausage.
Doses run generously, typically 1 to 4 g per kilo of meat, with the Tuscan and southern Italian formulas at the top of that range.