Moss is a small terrestrial plant, usually less than 10 cm tall, that lacks true conducting tissues (xylem, phloem) and has a dominant gametophyte (sexual) generation. Mosses are the largest and most highly developed group of division Bryophyta (which also includes liverworts and hornworts). Bryophytes are sometimes known as the “amphibians of the plant world” because of their dependence on water for sexual reproduction. There are over 10,000 species of moss worldwide, of which about 1,250 are found in North America. Individual parts of Canada have fewer species (e.g., 466 species in Alberta, 445 in Newfoundland, 430 in Ontario). Mosses thrive in humid climates, and coastal parts of Canada have a greater diversity than the interior parts.