Apium is a genus, as currently circumscribed by Plants of the World Online, of 12 species of flowering plants in the family Apiaceae, with an unusual highly disjunct distribution with one species in the temperate Northern Hemisphere in the Western Palaearctic (Europe, western Asia, north Africa), and the rest in the temperate Southern Hemisphere in southern Africa, southern South America, Australia, and New Zealand. They are prostrate to medium-tall annual, biennial or perennial herbs growing up to 1 m high in wet soil, often marshes and salt marshes, and have pinnate to bipinnate leaves and small white flowers in compound umbels. Some species are edible, notably Apium graveolens, which is the wild ancestor of the commercially important vegetables celery, celeriac and leaf celery.
The genus is the type genus of the family Apiaceae and the order Apiales; the type species of the genus is Apium graveolens.
