Parkia biglobosa (Jacq.) is an important leguminous tree crop in the African Savannahs useful to the natives where it is found, for domestic use. Previous diversity studies on this tree crop had been majorly on morphological and biochemical analysis. In order to capture the maximum diversity not obtained by previous research, the study aimed at evaluating the genetic diversity of accessions of this crop in the different agroecological zones in Nigeria using RAPD markers. A total of 81 scorable bands with an average of 8.1 bands per primer were amplified among the accessions studied. Intrazonal genetic diversity analysis showed a percentage polymorphism with a range of 11.11% to 65.43% among the agroecological zones studied. Although, gene diversity was highest within Humid forest agroecological zone, a low genetic distance and high genetic similarity between the agroecological zones were observed. Cluster analysis indicated six main groups of which four groups had single accessions while the two groups clustered the remaining accessions, indicating a narrowed genetic base from the 23 accessions studied. 1. Introduction The African locust bean plant (Parkia biglobosa) is a perennial tree legume belonging to the subfamily Mimosoideae of the family Fabaceae. It is one of the thirty-four known species of the genus Parkia whose centre of origin is South America. Distributed in a belt between latitudes 5°N and 15°N, and longitudes 16°W and 32°W, from the Atlantic coast in Senegal to Southern Sudan and Northern Uganda in the African continent, it has its greatest belt (about 800？Km) in West Africa and narrows to the east [1, 2]. Aside from its ecological role in cycling of nutrients [3, 4], it is a valuable source of food especially the seeds which serves as a source of useful spices for cooking [1, 5, 6]. Kwon-Ndung et al. [7] reported that it is a very important tree crop in the Africa Savannas where the natives use it as medicine, glaze for ceramic pots, fodder, firewood, and charcoal production. Parkia tree is also used as timber for making pestles, mortars, bows, hoe handles, and seats [8, 9] while the husks and pods are good food for livestock [10]. Previously, studies on diversity within this species focused on accessions from West African countries like Burkina Faso, Benin, and Uganda with only three accessions collected from the Southern Guinea Savanna in Nigeria [11–13]. These studies dealt majorly with phenotypic and anatomical diversity within species of the plant. P. biglobosa is however known to occur in diverse agroecological zones in Nigeria
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