Numerous Transitions to Land in Green Plants: The ‘Other’ Land Plants

Abstract

AbstractIn addition to the more conspicuous embryophyte group, numerous other green plant lineages have made successful transitions to land. Phylogenetic analyses using molecular data indicate that these lineages are primarily derived from freshwater ancestors, and include free‐living and lichen photobiont algae in the class Trebouxiophyceae, and several distinct lineages of free‐living algae in the class Chlorophyceae. In all cases, these independently derived land plants must possess adaptations for environments with reduced water availability, oxidative stress, and different light regimes than experienced by their aquatic ancestors. In the most extreme cases, these algae are living in very arid habitats. Given the monophyly of green plants and the evolution of independent terrestrial lineages from aquatic ancestors, these lineages represent natural experiments in the transition of green photosynthetic organisms to terrestrial living, and offer a rich source of taxa that can be compared experimentally with the embryophytes.