Non-flowering plants have several features in common, including reproduction by spores instead of seeds, and the absence of fruits and flowers. Non-flowering plants, unlike seed-bearing plants, may live on land or in water. These plants live in various locations; they are among the oldest plant species on the planet, and the first of these plants appeared in marine environments approximately 450 million years ago.
Non-flowering plants have simple and more primitive designs than flowering plants. These species include ferns, mosses, algae and lichen. Non-flowering plants are generally hardier than flowering plants; they live in extreme environments, including deserts and the cold Arctic tundra. Non-flowering plants reproduce using spores, which resemble seeds in size and function. Spores are the reproductive cells of non-flowering plants; they contain the genetic materials of plants, which are enclosed within hard outer casings or shells. Spores are released into the air or in water currents upon reaching maturation, and begin to germinate immediately upon landing, provided they have the basic environmental substances required for growth. When nutrients and water are scarce, however, spores can remain dormant until resources are readily available. The group of non-flowering plants includes more than 30,000 living species, which are further divided into 10 divisions. The most diverse division is that of gymnosperms, which contain conifers and needle-bearing plants.