Genus Peltophorum in Subfamily Caesalpinioideae

Genus Description

Peltophorum (Vogel) Benth. is a small genus in Fabaceae (legume family), subfamily Caesalpinioideae. About 10–12 species are recognized today, with a broadly Old World tropical distribution from Africa across South and Southeast Asia to the Pacific. The type species is Peltophorum pterocarpum (DC.) K. Heyne, widely planted along streets and in coastal groves and often regarded as the representative of the genus. The name is sometimes misspelled in horticultural literature, but the correct author citation is (Vogel) Benth. after the earlier description by Vogel (1840) later transferred by Bentham (1867).

The genus comprises trees or shrubs with bipinnate leaves bearing numerous small leaflets. New growth typically bears a rusty, stipitate-glandular or felty indumentum that matures to glabrescence; stipules are present but soon deciduous. Inflorescences are terminal or axillary panicles or racemes of numerous, actinomorphic, yellow to orange flowers. Sepals and petals number five each; stamens are ten, exserted, with anthers that often open by pores; the receptacle bears a conspicuous, obconical hypanthium. The ovary is superior, unilocular with a long style and capitate stigma; ovules are anatropous and attached to the adaxial suture. Fruit is a laterally flattened, thin-winged or narrowly marginate, indehiscent pod with a single seed that is usually dispersed as a whole.

Peltophorum attains its highest diversity in South and Southeast Asia, with P. africanum in tropical Africa and P. inerme extending into Malesia and the Pacific. Coastal forests, monsoon woodlands, riverbanks and seasonally dry lowlands are typical habitats, often near sea level but sometimes reaching mid-elevations in rainforest margins. Some species occur locally in sandy or limestone substrates.

Pollination is typically entomophilous, with generalized insects visiting the conspicuous, nectariferous flowers; the winged pods are wind-dispersed once they abscise. Nothing is well documented about breeding system or phenology beyond open, showy flowering spikes that attract a suite of pollinators and the derived, samaroid fruit morphology.

Taxonomically, Peltophorum sits in the “Peltophorum clade” of the mimosoidoid Caesalpinioideae, resolved in modern legume phylogenies as part of Cassieae sensu lato but often treated at subtribal rank as Peltophorinae (LPWG, 2013; 2017; Lewis et al., 2005). Modern treatments accept a narrow circumscription, with P. pterocarpum as core member and P. africanum widely maintained; older floristic works sometimes fused related genera (e.g., Baryxylum) into Peltophorum, but current consensus is to retain the latter as distinct and monophyletic (Polhill, 1994; Irwin & Barneby, 1982). The number of accepted species varies slightly among checklists and monographs, reflecting unresolved distinctions in Malesian taxa (POWO, 2024; WFO, 2024).

The genus is significant horticulturally—P. pterocarpum and P. africanum are common street and ornamental trees valued for dense shade and showy, yellow racemes—and locally for light timber and poles. It is not a major agricultural crop and does not feature prominently as an invasive in the current literature.

Conservation status is poorly documented across much of its range; coastal habitat loss and overexploitation for timber in parts of Asia present plausible threats, but standardized IUCN assessments are lacking. Phylogenetic work continues to refine species limits and geographic patterns, with a clear need for integrative taxonomy across the Old World tropics.

• Peltophorum africanum (Sond.)
• Peltophorum dasyrachis ((Miq.) Kurz)
• Peltophorum dubium ((Spreng.) Taub.)
• Peltophorum grande (Prain)
• Peltophorum linnaei (Griseb.)
• Peltophorum pterocarpum ((DC.) Backer ex K.Heyne)
• Peltophorum racemosum (Merr.)
• Peltophorum venezuelense (L.Cardenas & al.)