From The Food Encyclopedia by Jacques Rolland and Carol Sherman
a red-leafed chicory, Cichorium intybus, used in salads, originally from the Veneto region in northern Italy, with green leaves that turn red as the temperature falls. Although radicchio has been cultivated in southern France for a long time, Italy has cultivated it since the 16th century and is the world's primary producer. There are two main varieties, Verona and Treviso. Verona has burgundy red leaves with white ribs. It grows in a small loose-leafed head similar to butterhead lettuce. Treviso leaves are narrow and pointed. They are tighter and have tapered heads. The color varies from pink to dark red with white ribs.
