|Tibouchina semidecandra at Strybing Arboretum, San Francisco|
The family Melastomataceae (alternatively Melastomaceae) is a taxon of dicotyledonous flowering plants found mostly in the tropics (two thirds of the genera are from the New World tropics) comprising c. 165 genera and c. 5115 known species. Melastomes are annual or perennial herbs, shrubs, or small trees.
The leaves of melastomes are somewhat distinctive, being opposite, decussate, and usually with 3-7 longitudinal veins arising either from the base of the blade, plinerved (inner veins diverging above base of blade), or pinnately nerved with three or more pairs of primary veins diverging from the mid-vein at successive points above the base.
Flowers are perfect, and borne either singly or in terminal or axillary, paniculate cymes.
A number of melastomes are regarded as invasive species once naturalized in tropical and subtropical environments outside their normal range. Examples are Koster's curse (Clidemia hirta), Tibouchina semidecandra and Miconia calvescens, but many other species are involved.