Changes in Sex Ratio in Experimental Populations of Rumex Acetosella

Abstract

(1) Rumex acetosella is a dioecious perennial species which reproduces both by seeds and by adventitious shoots. The progression of the floral sex ratio was monitored for four years in experimental populations grown from seeds collected from five abandoned fields located south of Paris, France. At each census, all ramets in flower were scored for sex type. (2) In the first year, sex ratios were balanced, or slightly female biased. In the second year, sex ratios were seen to vary quite widely, depending on census date, population and also on the replicate sample within the population. In the third and fourth years male ramets greatly outnumbered females. Thus in the long term, male ramets showed greater clonal growth, i.e. recovered better than females following the repeated energetic cost of sexual reproduction. (3) The results of the present study suggest the importance of examining the age and past history of a population, as the relative contributions of sexual vs. vegetative reproduction may lead to different sex ratios depending on the time of establishment of the population.