Smallage is the wild variety of celery.
Smallage is very leafy, with thin hollow stalks and can grow up to 3 feet (1 metre) tall. The stalks are very slender and pliable.
It is a biennial plant. It grows the first year, blooms and seeds the next year, then dies.
Smallage blossoms with flat, umbrella-like masses of tiny white blooms, similar to parsley and Queen Anne's lace. It does look quite similar to parsley in a way, though the leaves' shape is different and the colour a bit lighter, and the stalks are a slightly thicker.
The stalks are very stringy and not very good eating. It is used as an herb for the strong, bitter flavour of its leaves. The raw leaves can be used in salads. Its seeds are what is sold as Celery Seed -- not seeds from celery plants but actually Smallage seeds. It can be treated as a cut and come again plant.
In France, Smallage is used in soups and stews, as they feel it gives more concentrated flavour then domesticated celery. One French name, "celeri à couper", gives the sense that it's to be cut up (and then tossed in a stew.)
Smallage was used historically as a flavouring in cooking, as a medicine, and in religious rites.
Literature & Lore
and with smallage dress my tomb:
And a cypress sprig thereto,
With a tear, and so Adieu."
-- Robert Herrick (1591 to 1674). "To Perenna, a mistress".
Smallage is sometimes thought to be what the Greeks called "selinon", but they used the same word for this and for parsley, so you can rarely know for sure what was meant. The Romans also used the same word -- apium -- for both smallage and parsley. Later both Latin and Greek came to have separate names for parsley. In Greek, πετροσέλινον ("petroselinon", "petros" meaning "rock" and "selinon" meaning "celery", so "rock celery"). From the Greek word, the Romans derived their more precise word of "Petroselinum". But as to what "rock" has to do with parsley is anyone's guess.