Lunularia

Lunularia is a genus of small liverworts in the family Lunulariaceae. The best-known species is Lunularia cruciata, commonly called the crescent liverwort, named for its crescent-shaped thallus lobes. It forms low, creeping mats on moist, shaded substrates and is often found on damp soil, rotting wood, leaf litter, or in potting mixes, greenhouses, and terrariums.

Description and morphology: The thallus of Lunularia cruciata is flat and green to yellow-green, typically only a few millimeters across. The lobes have a distinctive crescent outline, which gives the plant its common name. The upper surface may bear cup-like structures known as gemma cups, which contain gemmae used for asexual reproduction. Sexual reproduction occurs via the typical liverwort system, with male and female reproductive organs forming on different plants in many individuals, and fertilization requiring a thin film of water to allow sperm to reach archegonia. After fertilization, a short-lived sporophyte develops on the female plant.

Distribution and habitat: Lunularia cruciata has a broad distribution, preferring moist, shaded environments. It is a frequent inhabitant of damp soil, leaf litter, and decaying wood, and is commonly encountered in cultivated settings such as potted plants and terrariums.

Taxonomy and name: Lunularia is the genus, placed in Lunulariaceae. The name derives from Latin lunula, meaning a small moon, in reference to the moon-shaped lobes that characterize the species.

See also: liverworts (image group including Marchantia and Riccia).