Celeriac (Apium graveolens Rapaceum Group) is a specially selected Cultivar Group of celery, grown as a root vegetable for its large and well-developed taproot rather than for its stem and leaves.
The root is used when it is about 10-12 cm in diameter, or the size of a large potato.
Celeriac may be used raw or cooked. It is best to peel celeriac before use, since the outer skin is tough and stringy. It has the celery flavor, so it is often used as a flavoring in soups and stews; it can also be mashed or used in casseroles and baked dishes.
Nutritionally, celeriac is low in carbohydrates.
It is not as popular as other root vegetables, especially in the western hemisphere, very possibly because of its garish appearance before cleaning: it has been described as "a vegetable octopus" in reference to the tangle of rootlets that grow at the base.
There are numerous cultivars available, especially in Europe, where root vegetables are popular. Among the types are 'Prinz', 'Diamant', 'Ibis', and 'Kojak', which all received Royal Horticultural Society Award of Garden Merit designation in the year 2000 trials.
Celeriac has good keeping properties and should last three to four months if stored between 0° and 5° C and not allowed to dry out.