Bryophyte

bryophyte (division Bryophyta), any green, seedless plant that is one of the mosses, hornworts, or liverworts. Bryophytes are among the simplest of the terrestrial plants. Most representatives lack complex tissue organization, yet they show considerable diversity in form and ecology. They are widely distributed throughout the world and are relatively small compared with most seed-bearing plants. Most are 2–5 cm (0.8–2 inches) tall or, if reclining, generally less than 10 cm (4 inches) long. The division Bryophyta includes three main evolutionary lines: the mosses (class Bryopsida, or Musci), the liverworts (class Hepatopsida, or Hepaticae), and the hornworts (class Anthocerotopsida, or Anthocerotae). It is conservatively estimated that there are more than 1,000 genera and more than 18,000 species of bryophytes. Dating to early in the Ordovician Period (488 million to 444 million years ago), Bryophyta is the most ancient lineage of terrestrial plants.