For further information, contact Colin Hughes, Department of Plant Sciences, University of Oxford
The small Neotropical genus Leucaena (Leguminosae - Mimosoideae) comprises 22 species, 6 infraspecific taxa and two named hybrids. A new taxonomic monograph of Leucaena has recently been published (Hughes, C.E., 1998, Systematic Botany Monographs 55) building on an earlier revision of the Mexican species (Zárate, S., 1994, Anal. Inst. Biol. Mex. Ser. Bot. 65: 83-162).
The greatest diversity of species is in Mexico (17 species, 10 endemics) and northern Central America (9 species, 4 endemics). The genus extends north into southern Texas, U.S.A., sporadically across the Caribbean and into South America, as far south as Peru. All species are small to medium-sized trees which grow mainly in seasonally-dry deciduous tropical forest.
Map showing the total distribution of Leucaena in the New World. Data points are 2393 herbarium specimen collection sites with verifiable localities (88% of the total specimens examined). The map shows the occurrence of Leucaena species in seasonally dry tropical habitats and the virtual absence from cold desert regions and non-seasonal wet lowland forests.
The economic importance and domestication of Leucaena species, and particularly L. leucocephala for the production of livestock fodder, green manure, small wood products and for soil conservation is well-known and widely documented. Leucaena species are now cultivated pantropically as forage and wood crops. In Mexico, 13 species of Leucaena are used as minor food plants and have undergone a complex process of indigenous domestication. A Genetic Resources Handbook (Hughes, C.E. 1997. Tropical Forestry Paper 37, Oxford Forestry Institute) has been written to document these economically important genetic resources. Data and descriptive text covering main species attributes, botanical features and full botanical descriptions, tree size and form, taxonomy, species distributions, ecogeography, conservation status, utilisation, weediness, and chromosome numbers, have also been incorporated within the BRAHMS Leucaena Monograph.
L. collinsii, one of 22 species of Leucaena showing typical mimosoid bipinnate leaves and small flowers arranges in compact heads.
To order a copy of this monograph, contact:
Systematic Botany Monographs
University of Michigan Herbarium
North University Building Ann Arbor
MI 48109-1057 USA
American Society of Plant Taxonomists: http://www.sysbot.org
Further information on Leucaena and copies of publications are available from C.E. Hughes, Department of Plant Sciences, University of Oxford, South Parks Road, OXFORD, OX1 3RB, U.K. email: firstname.lastname@example.org