Dombeya is a large genus of flowering trees and shrubs in the family Malvaceae (order Malvales), traditionally placed in the now-subsumed family Sterculiaceae. It is one of the most species-rich genera in Malvaceae, containing up to 255 accepted species, though earlier estimates counted only around 80. The genus belongs to the wider mallow family alliance and is closely related to genera such as Pentapetes.
Plants in the genus are native primarily to sub-Saharan Africa, Madagascar, and the Mascarene Islands. Madagascar alone harbours approximately 175 native species, making it the centre of diversity for the genus. The African mainland holds around 19 species, and the Mascarene Islands (Réunion, Mauritius, and Rodrigues) have 24 species, of which 23 are endemic. One species, Dombeya acutangula, has a remarkable disjunct distribution, occurring in East Africa, Madagascar, the Mascarenes, and — unusually — Laos in Southeast Asia. Dombeya torrida extends from Central Africa north to Eritrea and into the southwestern Arabian Peninsula (Yemen and Saudi Arabia).
Members of the genus are typically trees or large shrubs bearing rounded clusters or pendant umbels of small, five-petalled flowers in shades of white, pink, or red. The resemblance of flowering branches to pear blossoms or hydrangea heads gives rise to common names such as "wild pear," "pink ball tree," and "tropical hydrangea," though Dombeya is unrelated to true pears (Pyrus) or hydrangeas (Hydrangea).
The genus name honours Joseph Dombey (1742–1794), a French botanist and South American explorer whose scientific collections became the subject of the "Dombey affair," a prolonged diplomatic dispute involving the governments of France, Spain, and Britain. Notable species include Dombeya wallichii (Pink Ball Tree), Dombeya torrida, and Dombeya cymosa of the Eastern Cape and KwaZulu-Natal.
Etymology
The genus name Dombeya commemorates Joseph Dombey (1742–1794), a French botanist and explorer best known for his botanical work in South America. Dombey's collections became the centre of the so-called "Dombey affair," a protracted controversy involving scientists and the governments of France, Spain, and Britain. Note that Dombeya of L'Héritier de Brutelle is an unrelated homonym, now a synonym of Tourrettia (Bignoniaceae), and Dombeya of Lamarck is a synonym of Araucaria.
Distribution
Dombeya is centred on Madagascar, which holds approximately 175 native species. Around 19 species occur on the African mainland, ranging from South Africa north to Ethiopia and west to West Africa, with Dombeya torrida also extending into Yemen and southwestern Saudi Arabia. The Mascarene Islands (Réunion, Mauritius, Rodrigues) host 24 species, 23 of which are endemic. A single species, Dombeya acutangula, has a disjunct occurrence in Laos, Southeast Asia.
Taxonomy
Dombeya is placed in the order Malvales. It has traditionally been assigned to Sterculiaceae, but modern phylogenetic systems (APG) include it in the broadened Malvaceae. Some checklists (including one GBIF treatment) recognise the segregate family Pentapetaceae for this clade. The genus contains up to 255 species in its current broad circumscription, absorbing many formerly distinct genera now treated as junior synonyms. The genus Astiria is suspected to be a nested derivative of Dombeya and may require inclusion. Several species have also been transferred from the still-valid genus Pentapetes.
