Turnera is a genus of more than 100 species of flowering plants in the family Passifloraceae (the passionflower family), placed within the order Malpighiales. The genus was formerly treated as the type genus of its own family, Turneraceae, which has since been merged into Passifloraceae under modern phylogenetic classifications. Species are predominantly herbs and shrubs, distributed across tropical and subtropical regions of the Americas, with centres of diversity in Brazil and the Caribbean.
The genus includes Turnera diffusa (damiana), a shrub native to the subtropical regions of Mexico and Central America that has a long history of medicinal and cultural use in Mesoamerica. Turnera ulmifolia (yellow alder or ramgoat dashalong) is among the most widely cultivated members, notable for its bright yellow flowers and tolerance of poor soils, making it a common ornamental in tropical gardens worldwide.
Floral diversity is a defining feature of the genus: many species exhibit distyly — a breeding system in which flowers occur in two morphological forms (pin and thrum) to promote cross-pollination — while some species are homostylous. The genus was named in honour of William Turner (1508–1568), the English naturalist and physician often regarded as the father of English botany.
Etymology
The genus Turnera was named in honour of William Turner (1508–1568), the English naturalist and physician regarded as the father of English botany. The name was formally applied by Linnaeus.
Distribution
Turnera is native to tropical and subtropical America, with the greatest species diversity concentrated in Brazil and the Caribbean. The range extends from Mexico and Central America through South America, with a small number of species reaching subtropical North America and the Galápagos Islands.
Taxonomy Notes
Turnera was long treated as the type genus of the family Turneraceae. Under the APG (Angiosperm Phylogeny Group) classification system, Turneraceae was subsumed into the broader Passifloraceae, placing Turnera within that family in the order Malpighiales. GBIF's backbone taxonomy still reflects the Turneraceae placement; the Passifloraceae treatment is recognised in more recent checklists.
