The growth of tree saplings, juvenile lianas and understorey shrubs was studied in a rain forest of north-east Gabon from 1980 to 1985. Five hundred individual plants belonging to more than one hundred species were marked along two transects, one
located in side the undisturbed forest and the other in a recent tree gap. The mortality of these plants during the 64 months' time interval, the growth in height, the percentage occurrence of traumas and the average leaf lifespan, were measured.
The different species of rain-forest plants developing starchy tubers were studied around Makokou (N. E. Gabon) and in the Lobaye River district (S. W. Central African Republic). A detailed description of the tuberous parts is given, particularly
in wild yams to help to elucidate the taxonomic status of a number of species. The different underground storage structures are considered as adaptive to the rain-forest environment. An estimate of the underground tuber biomass has been made. The benefits