Wild celery can be found classified as both an herb and a vegetable. It has slimmer stalks and more leaves than thick-stalked celery, both of which are used in cooking. It delivers more of a statement and creates a more authentic dish. It is available fresh in many large supermarkets and specialty greengrocers, and can be grown in pots at home. It should be used in smaller quantities than thick-stalked celery, and added to cooked dishes later in the cooking. Cooked, it may wilt quickly and look overdone, but it delivers on taste.
In appearance, the leaves look a lot like flat-leaf parsley, but crushing a leaf in your fingers will let you know which is which.
It is predominantly used in soups, casserole dishes, and salads.
Substitutes: Thick stalked celery with leaves can be used (in larger quantities), but the best substitutes are Chinese Celery or celery root. Grate or finely chop celery root when using raw (salads, etc.) and chop to use in cooked dishes.

