Cardoon is a herbaceous plant of very ancient origin, which belongs to the Composite family (like artichokes). It resembles a large celery, with spiny white or smooth ribs of a silvery color. Its height can reach up to one and a half meter. It is a typically winter vegetable, of which several varieties are known: the «Bolognese», the «Gigante di Romagna» and the «Riccio d'Asti» etc. There is also a type called "hunchback" which is obtained by burying the plant, curved, in the ground; it is a fairly common quality in Monferrato and central Italy. In the Chieri area a very tender cardoon is produced, suitable to be consumed with bagna cauda.
Whiter are the ribs and more tender is the cardoon; to keep them very white, it is usually cooked it in water with the addition of lemon juice and flour, after having deprived them of the fibrous filaments that run through them and cut into small pieces. The cooking time is quite long: about an hour and a half. When buying, it is good to avoid thistle which tends to reddish, because it has a bitter taste. As for the weight, it is necessary to count about 300 g of product per person.