Weinmannia is a genus of trees and shrubs in the family Cunoniaceae, order Oxalidales, comprising approximately 90 accepted species. Its range extends from Mexico through Central and South America and the Caribbean, reaching the Mascarene Islands of Mauritius and Réunion in the western Indian Ocean — a striking disjunct distribution that has made the genus of interest to biogeographers. The genus is absent from mainland Africa and Australia, although fossil material attributed to Weinmannia has been reported from Australia.
Plants in the genus are characterised by simple or pinnate leaves with toothed margins and interpetiolar stipules — a feature that helps distinguish them in the field. The small flowers are bisexual and white, borne in elongated racemes. The fruit is a capsule that splits vertically from the apex downward, releasing hairy, wingless seeds.
The taxonomic limits of Weinmannia have been actively revised. The genus was historically divided into five sections based on geography and morphology: Fasciculata (mostly Malesia, from Sumatra to Fiji), Inspersa (Madagascar), Leiospermum (mostly Pacific islands from the Bismarck Archipelago to the Marquesas), Spicata (Madagascar and the Comores), and the nominate section Weinmannia (Americas and Mascarenes). A 2021 phylogenomic study by Pillon et al. demonstrated that this broad circumscription rendered Weinmannia paraphyletic, with Old World and New World species forming two distinct lineages. The study proposed resurrecting the genus Pterophylla to accommodate the four Old World sections, leaving a narrower Weinmannia restricted to the Americas and the Mascarene Islands.
Distribution
Weinmannia occurs from Mexico through Central and South America and the Caribbean, with an isolated presence on the Mascarene Islands of Mauritius and Réunion in the western Indian Ocean. The genus is absent from mainland Africa and Australia, though fossil evidence suggests a broader past distribution.
Taxonomy Notes
Weinmannia was long divided into five sections spanning the Old and New World, but a 2021 phylogenomic study by Pillon et al. showed the genus as circumscribed is paraphyletic. The four Old World sections (Fasciculata, Inspersa, Leiospermum, Spicata) were proposed for transfer to the revived genus Pterophylla, with Weinmannia retained for the American and Mascarene clade (section Weinmannia) that is sister to that Old World assemblage.
