Pleroma is a genus of flowering plants in the family Melastomataceae, placed within the order Myrtales. Species are subshrubs, shrubs, or small trees native to tropical and subtropical South and Central America, with the greatest diversity in Brazil. They are recognized by their opposite leaves (often with petioles and frequently covered in scales or hairs), showy five-petalled flowers typically in purple or lilac tones, and ten stamens arranged in two whorls of five. The dry, semiwoody fruit capsule contains spirally coiled (cochleate) seeds.
The genus was originally described by David Don in 1823 but was subsequently absorbed into a broadly circumscribed Tibouchina by Alfred Cogniaux in his 1885 Flora brasiliensis treatment, which brought together some 470 taxa previously distributed across Chaetogastra, Diplostegium, Lasiandra, Pleroma, Purpurella, and related groups. This broad concept remained in use for over a century. A molecular phylogenetic analysis in 2013 demonstrated that the traditional, broadly defined Tibouchina was paraphyletic, and a follow-up study in 2019 formally proposed splitting it into four genera: a narrowly circumscribed Tibouchina, re-established Pleroma and Chaetogastra, and the newly described Andesanthus. GBIF currently recognizes 231 species within the re-established Pleroma.
Species such as Pleroma semidecandrum (formerly known in cultivation as Tibouchina semidecandra, the glory bush or princess flower) are widely grown in warm-climate gardens for their vivid purple blooms. The genus occurs naturally across the Americas from Mexico to northern Argentina and is particularly species-rich in Brazilian savannas and montane habitats. Several species have been introduced beyond their native range and are listed as noxious weeds in Hawaii due to their invasive potential.
Taxonomy Notes
Pleroma was first described by David Don in 1823 (Mem. Wern. Soc. 4: 293) but was lumped into a broad Tibouchina by Cogniaux in 1885 and remained there for over a century. A 2013 molecular study established that the broadly circumscribed Tibouchina was paraphyletic, comprising four distinct clades. A 2019 phylogenetic revision formally re-established Pleroma, along with Chaetogastra and the new genus Andesanthus, bringing the accepted species count to approximately 231 per GBIF.
Distribution
Pleroma species are native to tropical and subtropical America, ranging from Mexico and the Caribbean south to northern Argentina, with greatest diversity in Brazil. GBIF records range across Bolivia, Colombia, Costa Rica, Ecuador, French Guiana, Guatemala, Honduras, and Jamaica in addition to all major Brazilian regions. Several species have been introduced and naturalized in the Azores, Madeira, Comoros, Fiji, Mauritius, and Assam; introduced populations in Hawaii are classified as noxious weeds due to high invasive potential.
Ecology
Members of Pleroma and the broader former Tibouchina clade are found primarily in lowland savannas and on the lower slopes of the Andes. Some species have narrow endemic distributions known from only a handful of localities, while others have broader ranges across multiple countries. Where introduced outside their native range — particularly in Hawaii — several species are considered highly invasive and noxious weeds.
