Embryophyte

The embryophytes () are plants of the clade Embryophyta, also known as Plantae sensu strictissimo (, "plant in the strictest sense") or land plants. They are complex multicellular eukaryotes with haplodiplontic life cycles, all have specialized reproductive organs called sporangia, and reproduce sexually via alternation of generations using spores or seeds. The name "embryophyte" derives from their innovative characteristic of nurturing the embryonic sporophytes within the tissues of the parent gametophytes during the early stages of multicellular development. They are the dominant group of autotrophs that make up the vegetation on Earth's terrestrial and wetland ecosystems, and represent the quintessential concept of "plants" most familiar to the common knowledge. The study of embryophytes is called phytology. Embryophytes consist of the relatively species-poor non-vascular plants and the much more species-rich vascular plants (tracheophytes). The former are soft-bodied groundcovers that include three divisions of bryophytes, namely Bryophyta (mosses), Marchantiophyta (liverworts) and Anthocerotophyta (hornworts); while the latter are vertical-growing "higher plants" with lignified stem, absorptive roots and stomatous leaves, which include all extant polysporangiates such as lycophytes (clubmosses, firmosses, spikemosses and quillworts), polypodiophytes (ferns), gymnosperms (conifers, cycads, gnetophytes and gingko) and angiosperms (flowering plants). Since their boom during the mid/late Cretaceous, angiosperms have been the dominant group of embryophytes. Embryophytes are predominantly a terrestrial chloroplastidian clade that shared a common ancestry with freshwater green algae, having emerged within the Phragmoplastophyta clade of charophyte algae as a sister clade of Charophyceae, Coleochaetophyceae and Zygnematophyceae. They are informally called "land plants" because they have evolved to thrive primarily in the drier environment of upland areas above the high water marks (although some members having evolved secondarily to live once again in semiaquatic/aquatic habitats), while the closely related green algae are primarily aquatic and depend heavily on waterbodies to thrive. With very few exceptions, embryophytes are photoautotrophic and obtain metabolic biological energy by photosynthesis, using chlorophyll a and b to harvest light energy from sunlight for carbon fixation in order to synthesize carbohydrates, while releasing oxygen as a byproduct.