Etaballia dubia (Image: ©Bente Klitgård) > Kew Science > Projects > Tropical legume trees under the microscope

Tropical legume trees under the microscope

Systematic, taxonomic and floristic research focussed on the Pterocarpus and Brownea clades - two neotropical, ecologically and economically important groups of legume tree species.

Project details

Project Department: 
Project Leader: 
Funded By: 
Imperial College Doctoral Training Programme, Royal Botanic Gardens, Kew MSc course

Objectives and outputs

The Pterocarpus clade

The clade consists of 22 genera, about 200 species with Arachis (peanut), Pterocarpus (timber commonly traded as padauk and sangre de drago), and Platymiscium (timber commonly traded as Roble, Macacaúba, and Caóba) as the most speciose genera with 69, 25-40, and 19 species, respectively. Whilst Platymiscium was recently revised, the even more economically important Pterocarpus is in urgent need of taxonomic revision. In addition, members of this clade inhabit both dry and humid environments, and thus form a good model for understanding mechanisms for biome shifts in closely related taxa once a solid phylogeny and taxonomic framework have been built.

The Brownea clade

The members of this clade form a characteristic component of the lowland Amazonian tree flora, and they comprise around 125 species belonging to nine genera with two thirds of these in the likely paraphyletic Macrolobium. Species within the Brownea clade are particularly diverse in floral morphology, with phenological adaptations to attract a wide variety of pollinators like bats, humming birds, and hawkmoths. Using the Brownea clade as a proxy for Neotropical flowering plants, this project aims to build a broad, dated phylogeny of the Brownea clade to determine when species evolved with reference to ancient geological events, and accordingly to estimate speciation rates over time in order to see whether recent, rapid evolution led to the diversification of the Brownea clade.

Why Kew?

Kew has been a world centre for systematic legume research for centuries leading to a wealth of resources, including the world largest and best curated legume collections (about 700.000 herbarium specimens), and outputs like the series Advances in Legume Systematics with nine of 12 volumes published by Kew and Legumes of the World a Kew lead publication. The leader of this research programme has spent a large part of the past 25 years leading and participating in legume research projects mainly focussed on the Dalbergioid (including the Pterocarpus clade) and the Detarioid legumes (including the Brownea clade). Kew is therefore ideally placed to conduct the research outlined in the programme.


  • To gap-fill the existing phylogeny of the Pterocarpus clade with the aim to use it to: 1) revise species delimitation in the genus Pterocarpus; 2) asses conservation status of all Pterocarpus species; and 3) conduct biome shift and biogeographic analyses of the pantropical Pterocarpus.
  • To build a well-sampled phylogeny of the Brownea clade to be used to: 1) revise the generic delimitation in Macrolobium; and 2) the species delimination across the clade; and 3) to serve as model for understanding Amazonian species diversification and radiation, including which functional floral traits have evolved and determined the success of this radiation.


  • Integrated monographic account with IUCN assessments of Pterocarpus for a wide range of uses by foresters, conservationists, IUCN, border agencies, etc.
  • Dated phylogeny of the Brownea clade for use in biogeographic and speciation studies.
  • Generic classification of the Brownea clade.
  • An updated taxonomic framework for the Brownea clade genera (Brownea, Browneopsis, and Macrolobium) with updated circumscriptions of species, IUCN conservation assessments, key and descriptions for a wide range of uses by foresters, conservationists, IUCN, border agencies, etc.

Partners and collaborators


University of Montreal

Chicago Botanic Garden


Royal Botanic Gardens, Edinburgh


Bruneau, A., Klitgaard, B.B., Prenner, G., Fougére-Danezan, M. & Tucker, S. (2014). Floral evolution in the Detarieae (Leguminosae):  phylogenetic evidence for labile floral development in an early-diverging legume lineage. International Journal of Plant Science 175(4): 392-417. DOI: 10.1086/675574

Klitgård, B.B. (2005). Platymiscium (Leguminosae: Dalbergieae): biogeography, morphology, taxonomy and uses. Kew Bulletin 60(3): 321—400.

Klitgård, B.B. & Lavin, M. (2005). Dalbergieae s.l. In: Lewis, G., Schrire, B., Mackinder, B. & Lock, M. (eds.). Legumes of the World, Royal Botanic Gardens, Kew. pp307—335.

Klitgård, B.B., Forest, F., Booth, T.J., & Saslis-Lagoudakis, C.H. (2013).  A detailed investigation of the Pterocarpus clade (Leguminosae: Dalbergieae): Etaballia with radially symmetric flowers is nested within the papilionoid-flowered PterocarpusSouth African Journal of Botany 89: 128-142.  Notes:  11 IF 1.409  AvailElect

Pérez, A.J., Klitgård, B.B., Saslis-Lagoudakis, C. & Valencia, R. (2012). Brownea jaramilloi (Leguminosae: Caesalpinioideae), a new, over-looked species endemic to the Ecuadorian Amazon.  Kew Bulletin 68: 157-162.