Apium

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, 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.

Species

, Plants of the World Online accepts the following species:

Species formerly placed in this genus include:

Apium bermejoi → Helosciadium bermejoi
Apium inundatum → Helosciadium inundatum - lesser marshwort
Apium leptophyllum → Cyclospermum leptophyllum - marsh parsley, or fir-leafed celery
Apium nodiflorum → Helosciadium nodiflorum - fool's-water-cress
Apium repens → Helosciadium repens - creeping marshwort

Apium species, including garden celery, are eaten by the larvae of some Lepidoptera species including angle shades, common swift, Hypercompe icasia, the nutmeg, setaceous Hebrew character and turnip moth.