While found across Europe, North and South America, and Asia, it is considered rare in many areas, including Britain where it is classified as endangered.

Tortula cernua was described as a new species in 1833 by the German botanist Johann Wilhelm Peter Hübener in his work Muscologia Germanica; he initially classified it in the genus Desmatodon.

The leaves were described as crowded in tufts, lying overlapped like roof tiles, erect-spreading, small at the base and almost scale-like, becoming larger and broader above, oblong-ovate, sharply pointed, hollow, and entire-margined.

The capsule was described as very short egg-shaped, almost spherical, strongly curved over, nearly horizontal, smooth, yellow-green becoming light brown with age, and constricted at the reddish ringed mouth.

The cells of the leaf blade (lamina) near the tip are either hexagonal or rectangular in shape, measuring about 16–24 micrometres (μm) in width (though ranging from 13–28), and are typically smooth or rarely showing very slight surface bumps.

In northern Norway, masses of the springtail species Xenylla humicola have been observed moving among the apical leaves of fertile shoots, apparently attracted by sex-specific volatile compounds produced by the plants.

The spore capsules are either short-cylindrical and curved or egg-shaped and symmetrical along two sides, typically bent downward at an angle or occasionally positioned almost parallel to the ground.

The species is best distinguished by a combination of its distinctly bordered leaves with elongated narrow cells, nodding to horizontal and slightly curved capsules, and orange to brown peristome teeth that are not twisted, straight when dry, and deeply split into 32 branches that are often irregularly perforated.

In Switzerland, where it was last observed in 1942, it historically occurred in the eastern Central Alps and Ticino regions from hillside areas up to subalpine elevations at 200–1,500 m (660–4,920 ft).

In these areas, it grew on old, damp walls and rocks, preferring calcareous stone substrates like mortar and clay, as well as sandy-loamy soils.

The species can persist at suitable sites for long periods but is a poor competitor and can be overwhelmed by other bryophytes such as Didymodon tophaceus and vascular plants.

[3] The species' long-term survival in Britain is dependent on historic sites, as the highly alkaline lime kiln waste substrate is no longer produced and cannot legally be dumped in the environment without special consent.