embryophyte

Embryophyte, also known as land plants, is a clade of green plants whose embryos develop within maternal tissue. It includes the bryophytes (mosses, liverworts, and hornworts) and the tracheophytes (the vascular plants such as ferns, gymnosperms, and angiosperms), along with their fossil relatives. Embryophytes belong to the larger Streptophyta and are the sister group to certain charophyte algae within the green plants.

A defining feature of embryophytes is the retention and protection of the developing embryo within the tissues of the parent plant, along with an alternation of generations that includes a multicellular diploid sporophyte and a multicellular haploid gametophyte. They typically possess apical meristems, a waxy cuticle, and, in vascular lineages, specialized conducting tissues such as xylem and phloem. Spores are encased in resistant walls made of sporopollenin.

Reproduction and life cycles vary among the major groups. In bryophytes, the gametophyte is the dominant, photosynthetic stage, and the dependent sporophyte grows from it. In vascular plants, the sporophyte is the dominant life stage and is typically independent of the gametophyte. Fertilization produces a zygote that develops into a new sporophyte, which then produces spores by meiosis to continue the cycle.

Embryophytes colonized land early in plant evolution, developing adaptations such as the cuticle and stomata to regulate water loss, followed by vascular tissue and seeds in later lineages. This group forms the basis of nearly all terrestrial ecosystems.