Abstract: Humulus scandens is dioecious climbing herb. In the present study, wild H. scandens was grown in three ways, with tree support (height 3±0.5 m), shrub support (height 1±0.5 m) and no support, via artificial control. Biomass allocation, morphological and propagation characteristics were measured for each single plant. The aim of this study was to investigate the influence of external support on the morphological plasticity and reproduction strategies of H. scandens and the gender differences in using different external supports. The following results were observed. (1) The support significantly affected the stem, leaf and flower straits of branch and these traits showed gender differences. The stem and flower characteristics of female branches were vulnerable to the impact of external support, while leaf characteristics of male branches was vulnerable to the external support as well. (2) External supports caused significant gender difference in biomass allocation of branches. The plasticity of female plant was significantly higher than that of male plant. With increasing the height of external support, the stem biomass allocation ratio of female branches significantly decreased and its flower biomass allocation ratio increased. External supports had little effect on the flower and stem biomass allocation ratios of male branches. (3) For the female branches, external supports had a significant effect on the reproductive index and reproduction ratio (P<0.05) and a little effect on reproductive efficiency index. Male branches showed an opposite option. The external support had smaller effect on the reproductive characteristics of male plant than that of female. Thus, the female branches had higher reproductive plasticity than male branches.

Key words: latitude gradient, precipitation, ecological stoichiometry, common herbaceous plant, soil.