Since our knowledge concerning the time of fruiting of various Angiosperms is very limited, JACOBS (1969, 1970) recently recommended this subject to the attention of amateur-botanists. The present author is of the opinion that also attention should be paid to the study of the absence of ripe fruits. Various causes may be responsible for this aspect: spatial isolation of the sexes in dioecious species (Mercurialis perennis, Stratiotes abides), interspecific hybridization ( (Violahybrids), triploidy (a.o. Stellaria graminea) and predominance of vegetative reproduction (a.o. in Ranunculus ficaria and some strains of Potentilla anserina).