The story
From horn + wort (“plant”), from the fact that the spores are produced in slender horn-shaped structures.
Etymology from Wiktionary, CC BY-SA 4.0.
hornwort
Today it means: Any of certain bryophytes, of phylum Anthocerotophyta, with a leafless thallus characterized by a dominant gametophyte stage of the life cycle and a sporophyte stage shaped like a horn. Full definition →