Reproductive biology of Pentadesma butyracea (Clusiaceae), source of a valuable non timber forest product in Benin

Background and aims – The main reproductive traits of the native African food tree species, Pentadesma butyracea Sabine (Clusiaceae), which is threatened in Benin and Togo, were examined in Benin to gather basic data necessary to develop conservation strategies in these countries. Methodology – Data were collected on phenological pattern, floral morphology, pollinator assemblage, seed production and germination conditions on 77 adult individuals from three natural populations occurring in the Sudanian phytogeographical zone. Key results – In Benin, Pentadesma butyracea flowers once a year during the dry season from September to December. Flowering entry displayed less variation among populations than among individuals within populations. However, a high synchrony of different floral stages between trees due to a long flowering period (c. 2 months per tree), might still facilitate pollen exchange. Pollen-ovule ratio was 577 ± 213 suggesting facultative xenogamy. The apical position of inflore scences, the yellowish to white greenish flowers and the high quantity of pollen and nectar per flower (1042 ± 117 μL) represent floral attractants that predispose the species to animal-pollination. The main pollinators were two sunbirds ( Cyanomitra verticalis, Cinnyris coccinigastrus ) and three Hymenoptera ( Apis mellifera, Meliponula togoensis, Hypotrigona sp.). Mean fruit set reached 49%, and absolute fruit production increased with tree size. Seeds were desiccation-sensitive (i.e. recalcitrant) with a maximum duration of hydrated storage of three months. Germination of seeds was most successful and rapid at 30°C (50% after nine days). Conclusions – Our results indicate that the natural reproduction of P. butyracea is not limited by its ecology so that we hypothesize anthropogenic activities to be the reason for the threatened status of P. butyracea in Benin and Togo. However, due to its recalcitrant seeds, the conservation of its genetic resources is not feasible through ex situ conservation of seed banks but in situ strategies and/or ex situ conservation in orchards should be successful