For the genus of snails, see Acmella (gastropod).
Acmella is a genus of plants in the aster family, Asteraceae, described as a genus in 1807. It is native to the Americas and has been introduced to Asia, Africa, the Pacific islands, and Australia.

One familiar species is Acmella oleracea, which has been widely cultivated for centuries. It is used for food and medicine, and as an insecticide and an ornamental plant. Its common use as an herbal remedy for toothache and oral infections earned it the nickname toothache plant.

These are annual or perennial herbs with branching stems usually reaching 10 to 20 centimeters in length, growing prostrate or erect. The oppositely arranged leaves are smooth-edged or toothed, and usually have rough or soft hairs. The flower heads are usually solitary at the tips of the stem branches, or occasionally borne in inflorescences. There are several to many disc florets with bell-shaped throats and 4 or 5 triangular lobes, usually yellow, or sometimes orange. Some species lack ray florets, but some have 5 to 20 or more, usually in yellow or orange, but occasionally white or purple. The disc florets are bisexual, but any ray florets are pistillate.

Species

Accepted Species
Acmella alba (L'Hér.) R.K.Jansen
Acmella alpestris (Griseb.) R.K.Jansen
Acmella bellidioides (Sm.) R.K.Jansen
Acmella brachyglossa Cass.
Acmella calva (DC.) R.K.Jansen
Acmella caulirhiza Delile
Acmella ciliata (Kunth) Cass.
Acmella darwinii (D.M.Porter) R.K.Jansen
Acmella decumbens (Sm.) R.K.Jansen
Acmella filipes (Greenm.) R.K.Jansen
Acmella glaberrima (Hassl.) R.K.Jansen
Acmella grandiflora (Turcz.) R.K.Jansen
Acmella grisea (Chodat) R.K.Jansen
Acmella iodiscaea (A.H.Moore) R.K.Jansen
Acmella leptophylla (DC.) R.K.Jansen
Acmella leucantha (Kunth) R.K.Jansen
Acmella lundellii R.K.Jansen
Acmella oleracea (L.) R.K.Jansen
Acmella oppositifolia (Lam.) R.K.Jansen
Acmella paniculata (Wall. ex DC.) R.K.Jansen
Acmella papposa (Hemsl.) R.K.Jansen
Acmella pilosa R.K.Jansen
Acmella poliolepidica (A.H.Moore) R.K.Jansen
Acmella psilocarpa R.K.Jansen
Acmella pusilla (Hook. & Arn.) R.K.Jansen
Acmella radicans (Jacq.) R.K.Jansen
Acmella ramosa (Hemsl.) R.K.Jansen
Acmella repens (Walter) Rich. ex Pers.
Acmella serratifolia R.K.Jansen
Acmella sodiroi (Hieron.) R.K.Jansen
Acmella uliginosa (Sw.) Cass.
^ "The Plant List: A Working List of All Plant Species". Retrieved June 5, 2014.

source - Wikipedia