Variability among populations was analyzed in five provenances of Acacia nilotica
from spatially variable habitats. Populations of A. nilotica
developed in response to their habitat conditions. The level of variability was significantly high among the populations. Phenotypic variability was extremely high for leaf and stipular spine characteristics. The nature of morphological variability for vegetative traits appeared environmentally controlled. The differentiation of leaf and stipular spine expression seems to have an adaptive significance for the species in terms of water economy. Although, seed and podcharacteristics are geneticallycontrolled showing a lower proportion of variability but thesetraits supported r
that may allow the species to survive under a wide array of contrasting habitats. The study suggested that populations of A. nilotica
are differentiated in relation to the heterogeneity of environment. These populations became adapted to their habitat through the variability of morphological expressions. The morphologically differentiated populations of the species had allowed them to maintain themselves in a wide array of environmental situations enabling A. nilotica
to occupy ample ecological ranges.