The taxonomic key of identifiable aquatic smartweeds, Polygonum sp, is supplemented by a review of the merits and shortcomings of different members of the genus in water management. The second part of the bulletin reports the results of submergence trials conducted in temperature-programmed environmental chambers. The amphibious responses of Polygonum populations were appraised on the basis of mortality of shoots and leaves, and morphology and anotomy of plants. P. amphibium, var stipulaceum, and P. densiflorum showed the greatest amphibious response. A study of the plagiotrophy or prostrateness of P. amphibium varieties indicated that this property is partially genetically controlled and partly a function of the light-inhibited negative geotropism. (WRSIC abstract)