White clover, red clover, suckling clover, and lotus were grown under a controlled environment in soil to which phosphorus had been added at levels of 50, 250, 600, and 2000 ppm w/w. Growth analysis was used to explain differences in yield in terms of attributes describing growth, P uptake, and assimilation. The yield of white clover, red clover, and lotus increased markedly with P supply. Suckling clover responded less to P and its yields were smaller than those of the other species except that of lotus at 50 ppm. In all species the rate ofP uptake per unit root length increased with P supply. There were differences in uptake rate among species but these could not be consistently related to differences in yield. The efficiency with which absorbed P was used in the production of dry matter declined as the P supply increased in all species. Lotus used P with the greatest efficiency. Root/shoot ratios and root length/weight ratios were affected by an increase in P supply. Suckling clover had the highest root/shoot ratios, and lotus had the lowest. Suckling clover also had high root length/weight ratios. For these legumes, attributes such as root/shoot ratio, root length/weight ratio, P concentration, and inherent size appear to be more useful than P uptake in explaining response to P.