PHENOLOGICAL DIFFERENTIATION BETWEEN THE POPULATIONS AND SEXES IN THEPERENNIAL SPECIES RUMEX-ACETOSA

Phenological differences between populations and sexes of Rumex acetos a were investigated in experimental populations and in the natural see d source populations they were derived from. The male and female pheno logies were found to diverge late, shortly before sexual maturity, whi le differences between populations may occur early during seedling gro wth. The influence of early plant size on subsequent vegetative growth appeared inconsistent. The sex ratios were female-biased already amon g young seedlings, which suggests that pollen competition or different ial germination rates have some influence on the proportions of the se xes. Additionally, higher male mortality is likely to be partly accoun table for the even greater female bias observed in natural populations among mature plants. The degree of sexual size dimorphism at maturity appeared more extreme in the experimental populations than in the nat ural populations. This may be due to intraspecific competition in the high density conditions caused by intensive vegetative reproduction in the experimental populations.