Celeriac, also known as celery root or knob celery, is a variety of celery cultivated for its edible, knobby root rather than its stalks and leaves. Celeriac is a biennial plant that belongs to the same family as celery, Apiaceae (Umbelliferae). It produces a round or bulbous root that has a pale, knobby appearance. The root is the primary edible part and has a mild, celery-like flavour.