ABSTRACT
The origin of land plants is one of the most important events in biotic history. It is now well established that the ancestor of land plants was a fresh-water green alga (a charophyte alga). Based on fossil evidence, the land plants or embryophytes diverged from charophytes at least 475 million years ago (MYA). Once plants became established on land, they altered the terrestrial environment, and in doing so generated new niches that plants and other organisms could then inhabit. Plants faced numerous challenges on land, and they now possess many adaptations for terrestrial life. All land plants retain and nourish an embryo, have a complex body plan including an alternation of generations between sporophytes and gametophytes, and possess multicellular sporangia, antheridia, and archegonia.
