[3] First described by Palisot de Beauvois in 1805 from material collected in Philadelphia, it is a relatively large moss growing up to 5 cm (2 in) tall that forms loose to dense mats on calcareous substrates.

mucronatus, differs from the typical variety by having a shortly excurrent costa, smaller stature, and by growing as an earth moss rather than on rock.

The plants range in colour from light to dark green, though specimens found at higher elevations often take on a brownish tinge.

They have several distinctive features: the edges of each leaf have 3–4 rows of thick-walled cells forming a pale border, and the upper portions are marked by coarse, irregular teeth.

[5] Fissidens dubius grows primarily in calcareous (lime-rich) rock formations and other base-rich environments within forested areas.

[1] Within Switzerland, the species has been documented at elevations ranging from 200 to 2,400 m (660 to 7,870 ft) above sea level, and is found throughout the country's major geographical regions including the Jura Mountains, the Swiss Plateau, and the Alps.

The reproductive structures develop in specialised buds that form in the angles between the leaves and stem, concentrated in the middle portion of the plant.

When fertilisation is successful, spore capsules develop, which are carried on reddish stalks (setae) and positioned at a slight angle.

The species is classified as Least Concern (LC) in both European and EU 28 regional assessments due to its stable population trends and absence of major threats.