During the 1930's numerous atemoya seedlings appeared in Isreal. At that period Annona seedlings were used for planting and seeds were often obtained from fruit tree collections where A. cherimola and A. squamosa were planted in close proximity. Both species have protogyneous flowers; however they differ greatly in their flowering pattern. A. cherimola flowers open in the morning, are fully receptive for about 24 hr and shed their pollen in the afternoon. A. squamosa (one tree and its offspring) flowers open during the day and shed their pollen around 2 a.~. During the fir~t p~rt of A. cherimola flowering season flowers were found to open only on alternate days, with full synchronization on all trees. These flowering patterns tend to promote cross pollination between A. cherimola and A. squamosa. ----- Durante los a[(os treinta, mucha plantas de semillero aparecieron en Israel. En aquel entonces, se utilizaba las plantas de semillero de Anona para la plataci6'n y se obtenla frecuentemente las semillas en huertos donde se habra plantado la A. cherimola y la A. squamosa a poca distancia entre los arboles. Ambas especies tienen flores protogineas; sin embargo, tienen patrones de floraci6n muy diferentes, Las flores de la A. cherimola se abren por la maifana, son plenamente receptivas durante unas 24 horas y despues dejan caer su polen por fa tarde. Las flores de la A. squamosa (un ~bol y su progenie) se abren durante el dill y dejan caer su polen a eso de las dos de la tarde. Se note que, durante la primnera parte de la florescencia de la A. cherimole, las flores sOlo se abrtan cada tercer d(a, con plena simcronizacidn entre todos los arboles. Estos patrones de floracion tienden a favorecer la polinizacion cruzada entre la A. cherimols y la A. squemose.