Melanthera (common name: squarestem),[3] is a genus of perennial[4] flowering plants in the family Asteraceae, native to the tropical and subtropical Americas.

[2] Despite their general hardiness, leaves of Melanthera species are often attacked by rusts such as Uromyces columbianus and Uromyces martinii.

At times it included species native North and South America, as well as Africa, Asia and Oceania, including Hawaiʻi.

[6][7][8][9][10] Further studies are needed to clarify its taxonomic and phylogenetic relationships.

[11] The genus now includes three species native to the tropical Americas.