The detection of hybridity in Leucaena is discussed in relation to: (i) traditional criteria, (ii) molecular criteria and (iii) models to predict hybrid leaf morphology. Morphological, geographical and molecular evidence for the occurrence of interspecific hybrids between L. leucocephala and L. diversifolia in south-central Mexico, northern Guatemala, Jamaica, Dominican Republic, the Philippines and Papua New Guinea is presented. Predicted mean hybrid leaf trait values calculated from parent material are compared with data from putative hybrids and shown to be similar. The origin of these hybrids is discussed and shown to be the result of artificial sympatry resulting from indigenous, and recent exotic, domestication of the parent species. The hybrid is described as L. ×spontanea.
Plant Systematics and Evolution (1998) 212 (1/2) 53-77