The wild progenitor of cultivated cowpea (Vigna unguiculata ssp. unguiculata var. spontanea) is encountered in all humid lowland ecologies of Kenya, including the areas surrounding Lake Victoria, between 1000 and 1500 m in Central Kenya, and in the coastal plains. In the coastal plains, a second wild cowpea subspecies (V. unguiculata ssp. pubescens) is also encountered but hybridization between this subspecies and cultivated cowpea is not common. In all these areas, wild cowpea shows a weedy behavior and is much more present in disturbed areas, often in the vicinity of cultivated cowpea.  Genetic structure of representative populations as well as outcrossing rates (in natural conditions) are assessed using isozyme markers. Results suggest that gene flow between populations is low. Within populations, isozyme polymorphism is lower than expected (since some populations have an outcrossing breeding system) and may be too low to accurately really assess gene flow events.  Floral biology data, i.e. floral scent, nectar secretion, number of pollen grains and ovules, anthesis time, stigma receptivity, the anthers and stigma relative position of, and seed set are presented. Breeding systems range from total outcross (few wild populations) to inbred (in cultivated plants).  Pollinators are identified as carpenter bees and several Megachiles. They collect nectar and are normally visit each flower twice (at sunrise and once after the nectar is refilled). They do not exhibit flower color preferences or species prefences (when V. reticulata flowers are close to V. unguiculata flowers). They fly short distances while foraging and up to now, attempts to prove gene flow between plants beyond 50 m have failed.  Fitness of hybrids is assessed. F1 hybrids are obiously more fit than their parents, especially when one mother plant is a cultivated plants. They produce many seeds. However, these seeds are not dormant which may explain the low amount of hybrid plants found in natural populations.