Celery (Apium graveolens), a marshland plant variety in the family Apiaceae, has been cultivated as a vegetable since antiquity. Depending on location and cultivar, either its stalks, leaves, or hypocotyl is eaten and used in cooking.
Celery seed is also used as a spice; its extracts are used in medicines.
The plants are raised from seed, sown either in a hot bed or in the open garden according to the season of the year, and, after one or two thinnings and transplants, they are, on attaining a height of 15–20 cm (5.9–7.9 in), planted out in deep trenches for convenience of blanching, which is effected by earthing up to exclude light from the stems.
In the past, celery was grown as a vegetable for winter and early spring;
it was perceived as a cleansing tonic, welcomed to counter the salt-sickness of a winter diet. By the 19th century, the season for celery had been extended, to last from the beginning of September to late in April.
In North America, commercial production of celery is dominated by the cultivar called ‘Pascal’ celery. Gardeners can grow a range of cultivars, many of which differ from the wild species, mainly in having stouter leaf stems.
They are ranged under two classes, white and red. The stalks grow in tight, straight, parallel bunches, and are typically marketed fresh that way, without roots and just a little green leaf remaining.
The stalks are eaten raw, or as an ingredient in salads, or as a flavoring in soups, stews, and pot roasts.
In Europe, another popular variety is celeriac (also known, incorrectly, as celery root), Apium graveolens var. rapaceum, grown because its hypocotyl forms a large bulb, white on the inside. The bulb could be kept for months in the winter and mostly serves as a main ingredient in soup. It can also be ground up and used in salads. The leaves are used as a seasoning; the small, fibrous stalks find an only marginal use.
Leaf celery or Chinese celery, Apium graveolens var. secalinum, is a cultivar from East Asia.
The wild form of celery is known as “smallage”. It has a furrowed stalk with wedge-shaped leaves, the whole plant having a coarse, earthy taste, and a distinctive smell. The stalks are not usually eaten (except in soups or stews in French cuisine), but the leaves may be used in salads, and its seeds are those sold as a spice.With cultivation and blanching, the stalks lose their acidic qualities and assume the mild, sweetish, aromatic taste particular to celery as a salad plant.