Definition of apium:
(N) :
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.