Experimental Studies of the Mortality and Plasticity of a Weed

Summary. An attempt is made to show the ways in which a population of annual plants may react to increasing density so that the population becomes self‐regulatory. The reactions of Agrostemma githago to increasing density lake the form of increasing mortality and plastic response in the size and reproductive capacity of individuals. Experiments are described in which both of these reactions occur and it is shown that interference between Agrostemma and other species may influence either or both reactions. The significance of these observations for understanding the mechanism of natural selection is stressed. Etude expérimentale de la mortalité et de la plasticité d'une mauvaise herbe