hornwort

Nonvascular plant (with no ‘veins’ to carry water and food), related to the liverworts and mosses. Hornworts are found in warm climates, growing on moist shaded soil. (Class Anthocerotae, order Bryophyta.)

The name is also given to a group of aquatic flowering plants which are found in slow-moving water. They have whorls of finely divided leaves and may grow up to 2 m/7 ft long. (Genus Ceratophyllum, family Ceratophyllaceae.)

Like liverworts and mosses, the bryophyte hornworts exist in two different reproductive forms, sexual and asexual, which appear alternately (see alternation of generations). A leafy plant body, or gametophyte, produces gametes, or sex cells, and a small horned form, or sporophyte, which grows upwards from the gametophyte, produces spores. Unlike the sporophytes of mosses and liverworts, the hornwort sporophyte survives after the gametophyte has died.