The Collaborative International Dictionary of English v.0.48:

Smallage \Small"age\, n. [Small + F. ache smallage. See Ach
   parsley.] (Bot.)
   A biennial umbelliferous plant (Apium graveolens) native of
   the seacoats of Europe and Asia. When deprived of its acrid
   and even poisonous properties by cultivation, it becomes
   celery.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Apiaceae \Apiaceae\ prop. n.
   A natural family of plants bearing flowers in umbels;
   examples are: parsley; carrot; anise; caraway;
   celery; dill.

   Syn: Umbelliferae, family Umbelliferae, family Apiaceae,
        carrot family
        [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

Celery \Cel"er*y\, n. [F. c['e]leri, cf. Prov. It. seleno,
   seler; fr. Gr. ? parsley, in Lgr. & NGr. celery. Cf.
   Parsley.] (Bot.)
   A plant of the Parsley family (Apium graveolens), of which
   the blanched leafstalks are used as a salad.
   [1913 Webster]

WordNet (r) 3.0 (2006):

celery
    n 1: widely cultivated herb with aromatic leaf stalks that are
         eaten raw or cooked [syn: celery, cultivated celery,
         Apium graveolens dulce]
    2: stalks eaten raw or cooked or used as seasoning