Twelve species ofAnnonaceae, namelyAncana sp.,A. stenopetala, Annona cherimola, A. montana, A. muricata, A. squamosa, Bocagea sp.,Bocageopsis canescens, two species ofUnonopsis, Xylopia aromatica, andX. emarginata, were investigated with respect to the morphology and anatomy of the seed. They show the basic structural pattern characteristic of annonaceous seeds: perichalaza, fibrous mesotesta, and rumination developed by both integuments. However, several differential characters, some of them never previously described, were found: All taxa exhibit an additional endotestal mechanical layer which forms the micropylar plug except inAncana. InAncana the plug is built by the inner integument. Aril, sarcotesta and pits on the seed surface are present in some taxa and show different origin and structure. Special anatomical adaptations possibly functioning during germination are described. The results obtained from the investigated taxa are discussed and compared with published data on seed structure inAnnonaceae.