''Acmella'' is a genus of plants in the family Asteraceae, described as a genus in 1807.Tropicos, ''Acmella'' Pers.
/ref> It is native to the

Americas The Americas, which are sometimes collectively called America, are a landmass comprising the totality of North and South America. The Americas make up most of the land in Earth's Western Hemisphere and comprise the New World. Along with th ...

and has been introduced to Asia, Africa, the Pacific islands, and

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

. One familiar species is '' Acmella oleracea'', which has been widely cultivated for centuries. It is used for food and medicine, and as an

insecticide Insecticides are substances used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. Insecticides are used in agriculture, medicine, industry and by consumers. Insecticides are claimed to b ...

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 A pseudanthium (Greek for "false flower"; ) is an inflorescence that resembles a flower. The word is sometimes used for other structures that are neither a true flower nor a true inflorescence. Examples of pseudanthia include flower heads, compos ...

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

References

External links

*
GRIN Species Records of ''Acmella''.
Germplasm Resources Information Network (GRIN). Asteraceae genera {{Heliantheae-stub