The genus includes 248 species of small plants that typically grow as green, scaly patches on tree trunks, logs, or rocks in moist environments.

It is distinguished from other liverworts by several unique features, including the production of root-like structures (rhizoids) exclusively from leaf surfaces and characteristic branching patterns.

The oldest known fossil species, R. cretacea, found in Burmese amber, dates to the Cenomanian age, though molecular evidence suggests the genus originated in the Triassic period, around 228 million years ago.

However, in the late 1970s and early 1980s, several bryologists including Eustace Wilkinson Jones (1977),[4] Kohsaku Yamada (1979),[5] and Rudolf Mathias Schuster (1980)[6] challenged this broad interpretation.

These researchers advocated for a return to Richard Spruce's original narrower concept from 1885,[7] which was supported by detailed morphological characteristics including stem anatomy and patterns of leaf insertion.

The first infrageneric classification was published by Franz Stephani in 1884, dividing the then-known 92 species into 12 sections based on readily observable characteristics like leaf shape and growth habits.

The subgenus Cladoradula, comprising seven species, was found to have diverged during the late Permian period about 263 million years ago, making it one of the oldest lineages within the family.

[8] Radula species are leafy liverworts that typically appear as a scaly, green surface on tree trunks, logs, or rocks in sheltered, moist outdoor environments.

This shift to combined sexes appears to have happened multiple times independently in different Radula species, suggesting it provided evolutionary advantages.

These tree-dwelling species tend to reproduce by breaking off fragments of their plant body rather than producing specialised reproductive structures called gemmae.

The current distribution of some Radula groups appears to have been shaped by the ancient breakup of the supercontinent Gondwana, as evidenced by the timing of their evolutionary splits coinciding with continental separation events.

This is particularly noteworthy because liverworts typically produce tiny spores that can be carried long distances by wind, which usually erases such ancient geographic patterns.

The restricted ranges of some Radula groups appear to be due to their environmental preferences being conserved over evolutionary time, rather than an inability to disperse to new areas.

R. oblongifolia and R. sphaerocarpoides are found in both amber deposits, suggesting these morphological forms persisted for several million years, though they may represent multiple biological species that appear similar.

Research has shown that perrottetinene can cross the blood-brain barrier and cause effects like lowered body temperature and reduced movement in laboratory studies.