Phenological differentiation between the sexes of Rumex hastalulus: niche partitioning or different optimal reproductive strategies

At two sites in North Carolina, inflorescence heights, leaf number at various height intervals, and time of senescence were studied over the flowering season of Rumex hastatulus, an annual dioecious colonizer. Inflorescence height was significantly affected by site, census date, and sex. Female inflorescences rapidly outgrew males, though males began flowering first. Leaf number was significantly affected by site, height interval, and sex at all census dates. Females had more leaves than males. The mean senescence date of males was one week earlier than for females. The differences reported for males and females are best interpreted as consequences of the different optimal reproductive strategies of the two sexes rather than as niche partitioning of the light resource.