63. Acmella Rich. ex Pers.
(Jansen, 1985)
About 30 species,
North America to South America, Caribbean Islands, Africa, Asia south to
Australia.
Jansen (1981)
discussed the variety of morphological features separating Acmella from
the closely related genus Spilanthes Jacq., to which the Missouri
species was assigned by most earlier authors (Steyermark, 1963).