It has a Holarctic distribution, occurring across Eurasia and North America,[4] where it typically grows on tree bark and rocks in areas with adequate rainfall.

The species was first described by Carl Linnaeus, with early descriptions and illustrations provided by Pier Antonio Micheli (1729) and Johann Jacob Dillenius (1741).

[5] A comprehensive 1998 study examining both morphological and genetic variation in Porella platyphylla and P. platyphylloidea led to a significant taxonomic revision.

The research, which analysed 35 populations across North America and Europe, revealed three distinct genetic groups within what had previously been considered two separate species.

To help stabilize the taxonomy of this complex group, researchers later designated a DNA voucher specimen from Germany (Heinrichs and Feldberg 4600) as an epitype for P. platyphylla.

[7] A key identifying feature of the species is found in its perianth—a protective tube-like structure that surrounds the developing reproductive organs in female plants.

The female reproductive structures (called bracts) typically have smooth, unbroken edges, unlike some related species which may have toothed or spiny margins.

[7] Features previously used to distinguish P. platyphylla from P. platyphylloidea, such as leaf lobule width and elater spiral patterns, have shown no consistent correlation with genetic groupings.

While some tendencies exist, such as larger leaf lobules being more common in North American populations, these characteristics are not consistent enough for reliable identification.

Like other liverworts, this species displays distinct stages in its life cycle, including both a dominant gametophyte (the main plant body) and a smaller sporophyte phase.

[8] Studies using chlorophyll fluorescence measurements have shown that the species can recover rapidly and completely after spending a week in an air-dry state.

[9] During drying, the plant's photosynthetic efficiency remains near optimal until water content falls below about half of the fully hydrated state, after which it declines steeply.

[11] The chemical composition of Porella species, particularly their terpenoid profiles, has proven valuable for taxonomic investigations, helping to resolve uncertainties in this morphologically challenging genus through correlation with molecular data.

The species shows distinct geographical structuring in its genetic makeup, with European and North American populations forming separate sister clades.

While the species is capable of long-distance dispersal—as evidenced by its wide distribution—molecular evidence suggests that successful establishment and genetic mixing between distant populations remains relatively rare.

[6] Whilst the species is widespread in Europe, the typical European form (P. platyphylla sensu stricto) has been confirmed from only a single locality in New Mexico in North America.

[12] Within Russia, most occurrences lie between 43° and 45°N, though the species penetrates northward to several locations including the Bolshoy Anyuy (49°N), Komsomolsk Nature Reserve (51°N), and the Dzhagdy Range (~54°N).