The legumes (family Leguminosae) are the third largest family of flowering plants, with about 19,500 species. Legumes provide food crops, timber, fodder and shade, and fertilise poor soils by nitrogen fixation in their roots.
Legume trees dominate many of the world's most species rich tropical forest ecosystems, but many require basic taxonomic study in order to catalogue their species. For this reason, taxonomic monographs of these genera are a key focus of our research. (See Monographs below.)
We are estimating phylogenies in some of these genera as part of our work in Environmental Change and Biogeography, with particular emphasis on developing a phylogeny for the neotropical genus Inga.
Broad-scale evolutionary relationships within the legumes have also been poorly understood, meaning that the true relationships of economically important, evolutionarily derived groups such as peas, beans, soya and lupins, remain obscure. We are contributing molecular systematic data to global efforts to elucidate legume phylogeny (See generic relationships, below). Our final research area is in legume flower evolution.
Taxonomic monographs enable accurate identification of all species and summarise information on their uses, distribution and biology.
The Garden has provided monographs of Geoffroea, Cyclolobium, Andira, Berlinia, Plathymenia, Cenostigma and Barnebydendron. Current work focuses on Lathyrus and Dussia (Papilionoideae).
Berlinia wood is commercially logged in parts of its range although difficulties in distinguishing species, often compounded by several species being known by the same vernacular name, (e.g. Ebiara), can be an obstacle to assessing the extent of logging of a given species. Commercial forestry is just one of several factors that threaten the conservation of the biodiversity of Berlinia. Others include mining activities, land clearance for agriculture and pressure of human population. Half of the known species of Berlinia qualify for a category of threat as defined by the International Union for the Conservation of Nature. A monograph of Berlinia has recently been published. It includes keys, distribution maps, detailed descriptions, species conservation assessments and present the results of a phylogenetic study which investigated inter- and intra-generic relationships and explored the historical biogeography of the genus.
Lathyrus (the ‘sweet peas'), is the largest genus in tribe Fabeae, the group that contains the true peas (Pisum), lentils (Lens) and vetches (Vicia). Collaborations between RBGE and the University of Tokyo have investigated the molecular phylogenetics and biogeography of Lathyrus. This ongoing study confirms the close relationship between Lathyrus and Pisum, and suggests a Eurasian origin for the South American American lineages. A monograph of the mainly S. American section Notolathyrus is being prepared for publication.
MacKinder, B. & Pennington, R.T. (2011). A monograph of Berlinia (Leguminosae: Caesalpinioideae). Systematic Botany Monographs 91 (117 pp.)
Warwick, M. & Lewis, G.P. (2009). A revision of Cenostigma (Leguminosae - Caesalpinioideae). Kew Bull. 64: 135-146.
Warwick, M. & Lewis, G.P. & de Lima, H.C. (2008). A reappraisal of Barnebydendron (Leguminosae – Caesalpinioideae). Kew Bull. 63: 143-149.
Mackinder, B.A. & Harris, D.J. (2006). A synopsis of the genus Berlinia (Leguminosae – Caesalpinioideae). Edinburgh Journal of Botany 63(2-3): 161-182.
Pennington, R.T. (2003). A monograph of Andira (Leguminosae-Papilionoideae). Systematic Botany Monographs. 64: 1-145.
We have used DNA sequence data to reconstruct phylogeny of in several areas of the legume family. RBGE is playing a leading role in the Legume Phylogeny Working Group, an international effort of numerous researchers that aims to develop collaborative research towards a comprehensive phylogeny and classification for Leguminosae. Molecular phylogenies are a powerful tool for comparative biology. They have allowed a re-evaluation of how features such as legume flowers have changed over evolutionary time and will be used to future studies studies of tropical biome assembly: http://www.rbge.org.uk/science/tropical-diversity/environmental-change-and-biogeography/community-assembly.
Legume Phylogeny Working Group (submitted). Legume phylogeny and classification in the 21st century: progress, prospects and lessons for other species-rich clades. Taxon (40 authors including Barbara MacKinder, Greg Kenicer and Toby Pennington (as corresponding author).
Cardoso, D., de Lima, H.C., Schütz Rodrigues R., de Queiroz, L.P., Pennington, R.T. & Lavin, M. (2012). The realignment of Acosmium sensu stricto with the Dalbergioid clade (Leguminosae, Papilionoideae) reveals a proneness for independent evolution of radial floral symmetry among early branching papilionoid legumes. Taxon.
Mackinder, B.A., Wieringa, J.J., Lunenburg, I. & Banks, H. 2010. Challenges and progress in clarifying the generic limits of Talbotiella and Hymenostegia (Detarieae: Caesalpinioideae: Leguminosae). Proc. 18th AETFAT Congress: 43--56.