Cytological Study on Sterility in Salvinia auriculata Aublet with a Bearing on Its Reproductive Mechanism

Salvinia auriculata Aublet under cultivation in several places in India and Rhodesia, S. Africa is pentaploid and show 2n=45 in leaf tip squashes.Analysis of mega- and microsporocarps reveals respectively 62 per cent and 45 per cent abortive sporangia in which meiosis fails to occur and archesporium degenerates. In the functional mega- and microsporangia the course of meiosis is typical of the pentaploids. A high percentage of spore mother cells show failure of cytokinesis both at the close of first and second division resulting in monads which lack well organized nucleus. The above alongwith other irregularities of meiosis offset normal spore formation, completely.The presence of multivalents indicates homology between the parental genomes to a fair degree. On this basis intraspecific origin of the present taxon is surmised.The archesporium is eight-celled in both the types of sporangia. A reference to previous literature especially Mahabale and D'Mello (1952) shows that on this criterion apogamous reproduction was inferred. It is discussed that the eight-celled archesporium is not indicative of apogamy since other features of apogamy that follow eight-celled archesporium are totally lacking. Finally the role of vegetative apomixis in preserving sterile races of heterosporous ferns is discussed.