TEMPORAL PATTERNS IN THE DEVELOPMENT OF SEXUAL DIMORPHISMS IN SILENE-LATIFOLIA (CARYOPHYLLACEAE)

Sexual dimorphisms in Silene latifolia Poiret (=S. cucubalus Wibel) developed in two different time frames during the first year of growth. Traits correlated with flower number became sexually dimorphic as soon as flowering began while the remaining sexually dimorphic traits developed intersexual differences after females matured a relatively large number of fruits. There was no sexual dimorPhism in green leaf area, although leaf surface area decreased during reproduction in both sexes. Biomass allocation to leaves also decreased in both males and females during reproduction. The main stem of both sexes grew in weight but not in height after reproduction began, with females adding more biomass per cm than males. Females accumulated more biomass than males in the latter half of the annual growth period, despite higher reproductive effort. Several hypotheses are suggested to explain this result: 1) females allocate less biomass to supporting structures, 2) carbon gain by immature fruits, 3) females may be physiologically active for a longer time period in order to complete fruit maturation, and 4) possible higher resource-use efficiency by females.