A Piptostigma pilosum B Piptostigma submontanum C Polyceratocarpus microtrichus D Polyceratocarpus parviflorus E Polyceratocarpus pellegrinii F Sirdavidia solannona G Sphaerocoryne gracilipes H Toussaintia hallei I Uvaria afzelii. White borders represent region limits in Cameroon; green patches represent protected areas (see methods and Suppl. material 1: Fig. S1).