Hornwort is the name of a group of small, nonflowering plants that somewhat resemble mosses and liverworts. There are hundreds of species (kinds) of hornworts. They are found throughout the world but are especially common in tropical regions and in warm, moist climates. Hornworts grow mainly on bare, damp, shaded soil. They are often found along roadsides or near edges of streams or lakes.
A hornwort reproduces in a cycle called alternation of generations. It has two distinct forms during its life cycle, the gametophyte and the sporophyte. The gametophyte is made up of a simple plant body called the thallus. The thallus looks like a mound of ruffled, dark-green leaflets. It grows along the ground and is usually 3/8 to 3/4 inch (1 to 2 centimeters) across. The thallus is anchored to the soil by rootlike structures called rhizoids. The sporophyte is long and slender. It may be from 3/16 to 43/4 inches (0.5 to 12 centimeters) high. The sporophyte grows upward from the thallus and resembles cattle horns, giving the plant its name.
