Land plants are rooted in one place, yet must be able to disperse their offspring to minimize competition for space and resources with the parent plant. Early-diverging groups of plants evolved the capacity to disperse their offspring through the air, but they still required water for fertilization. How could these plants exist in both water and air? They couldn’t—at least not at the same time. Instead, early land plants evolved a life cycle in which one generation, or phase of the life cycle, released sperm into a moist environment and the following generation dispersed offspring through the air. Thus, a pattern of alternating haploid and diploid generations, which occurs in all plants, is thought to have evolved as a means of allowing fertilization in water while enhancing the dispersal of offspring on land.