It is known that the efficient dispersal is one among other features that amplify the invasion potential of a plant. Knowledge of the ontogeny, morphology and fruit dispersal of species is indispensable for weed control in crops. To identify the pericarp structures involved in the fragmentation and dehiscence processes and other features related to dispersal, we studied the pericarp development of Aeschynomene evenia Wright, Desmodium incanum (Sw.) DC. and Vigna luteola (Jacq.) Benth. (Fabaceae-Faboideae), all of which are considered weeds in certain situations. For light and scanning electron microscopy studies, we fixed and processed buds, flowers and fruits, according to usual methods, at different stages of development. We observed that the sclerenchymatous endocarp is essential for dehiscence in legumes, as well as for fragmentation in loments. We also found that the presence of hook-shaped trichomes, sclereid nests in the mesocarp, septum, hypodermis and the formation of false septa are essential to the diaspore dispersal of the species studied.