Fennel vegetable Florentine (Foeniculum Vulgare ssp. Vulgare (Miller) Thell) Fennel French (Foeniculum Vulgare ssp. Vulgare (Miller) Thell) is also called Italian, Florentine or vegetable. It is a biennial plant of the Celery family (Apiaceae), 40-60 cm tall. It is grown for the sake of thickening the fleshy bases of the leaf petioles. White onion-shaped thickenings have the taste of anise, they are used in raw and boiled form. Strongly dissected French fennel leaves are used as a seasoning instead of ordinary fennel.