Résumé
Gynodioecious populations (i.e. populations with female and hermaphrodite individuals) often contain a third phenotype with an intermediate sex expression. In Silene italica, this phenotype is characterized by a mixture of pistillate and perfect flowers and is thus gynomonoecious. To characterize sexual functions of these gynomonoecious individuals and their potential influence in the maintenance of gynodioecy, reproductive characters of the three sexual phenotypes were compared over 2 years in several families of S. italica produced by crossing. We found that gynomonoecious individuals were intermediate for flower production and female fertility characters, although they did not always significantly differ from female individuals. Perfect flowers of gynomonoecious and hermaphrodite plants were similar in size and pollen production. Gynomonoecious individuals were thus intermediate in female and in male functions. Family effects were found for most of the characters. The female advantage (i.e. the fertility of females compared to the female fertility of pollen producing plants) was not dramatically different when gynomonoecious plants were taken into account. (c) 2006 The Linnean Society of London.