The role of branching on the development of size hierarchies was studied on experimental populations of the annual herbGalium aparineL. (Rubiaceae). All branches of plants growing at high and low density were severed as plants developed, and the growth of individual plants, the development of growth and size inequalities, and the mean change in the size ranking of plants over time were compared with those of populations of naturally branched plants. Size allometries were analysed for all treatments. The effect of the branch-severing treatment on growth and size inequalities was not significant for crowded populations. The position of individual plants in the ranking of weights in crowded conditions was less variable for populations of unbranched plants than for those of branched plants. Size and growth inequalities among branched plants were not significantly affected by population density. The hypothesis that branching increases the development of competitive hierarchies inG. aparinepopulations is not supported by the results. The role of height growth limitation in crowded conditions as a constraint to competitive hierarchy development is discussed.Key words: allometry, branching pattern, competitive hierarchy,Galium aparine, intraspecific competition.