Plant evolution: landmarks on the path to terrestrial life

Photosynthetic eukaryotes thrive anywhere there is sunlight and water. But while such organisms are exceptionally diverse in form and function, only one phototrophic lineage succeeded in rising above its substrate: the land plants (embryophytes). Molecular phylogenetic data show that land plants evolved from streptophyte algae most closely related to extant Zygnematophyceae, and one of the principal aims of plant evolutionary biology is to uncover the key features of such algae that enabled this important transition. At the present time, however, mosaic and reductive evolution blur our picture of the closest algal ancestors of plants. Here we discuss recent progress and problems in inferring the biology of the algal progenitor of the terrestrial photosynthetic macrobiome.