moss

Small nonflowering plant of the class Musci (10,000 species), forming with the liverworts and the hornworts the order Bryophyta. The stem of each plant bears rhizoids that anchor it; there are no true roots. Leaves spirally arranged on its lower portion have sexual organs at their tips. Most mosses flourish best in damp conditions where other vegetation is thin. There are 1,000 British species of moss and more than 1,200 North American species.

The peat or bog moss Sphagnum was formerly used for surgical dressings. The smallest moss is the Cape pygmy moss Ephemerum capensi, only slightly larger than a pin head.