The evolution of plants has resulted in widely varying levels of complexity, from the earliest algal mats, through bryophytes, lycopods, ferns to the complex gymnosperms and angiosperms of today. While many of the groups which appeared earlier continue to thrive, as exemplified by algal dominance in marine environments, more recently derived groups have also displaced previously ecologically dominant ones, e.g. the ascendance of flowering plants over gymnosperms in terrestrial environments.