The influence of environmental conditions on the epicuticular waxes of the normal and four mutant forms of brussels sprout (Brassica oleracea var. gemmifera) has been studied. An increase in radiant energy rate, a decrease in humidity or a decrease in temperature induces the largest deposits of wax. Environmental conditions have only a limited effect on the compositions of the waxes of the normal and mutant lines but modify the size, configuration and distribution of the surface wax structures. A mechanism for the transport and subsequent organization of the wax on the plant surface is discussed.