The differentiation between this genus and other genera of the family is not very clear. In most cases the leaves of members of this genus are lingulate, i.e. broadest in the middle or in the upper part of the leaf. In many species the midrib excurs as long, serrate hyline hair.
In the lower half of the leaves the cells are nearly without chlorophylle, narrow rectangular and smooth. In the upper half they are smaller, round and more or less opaque, because they are very papillose.
The cylindrical capsules always are sitting erect on a long seta, and they have a long rostrate operculum. The 32 peristome teeth are contorted.
In total the genus contains about 300 species, of which 20 can be found in Europe.
Tortula muralis forms low (about 5mm high) turfs on walls. In humid state it is easy to recognize by it broad, yellow-green (or blue-green) leaves. They end more or less obtuse and with a long, white hair. In dry state the moss is blackish or glistens gray because of the glass hairs. In any case it is then not so easy to recognize.
The seta and the capsule are reddish. The peristome teeth are twice until three times contorted to the left.
Tortula muralis is one of the most frequent mosses on walls, roofs or on rocks. It does not prefer such sunny places as Grimmia pulvinata, but is able to endure extreme dryness. (It is said, that the species survives temperatures until 70°C and continues growing even after 14 years in dry state.)
This species too is rather frequent. It grows on earth, on rocks, walls or on concrete in natural environments just as on the side of roads.
The rather robust, often until 8cm high, in most cases 2-3cm high plants form cushions, which are often rather colorful (light green, yellowish green, reddish, brownish until black green). The long hyaline hairs of the leaves can clearly be seen with the naked eye. Under the microscope one can see, that those hairs are irregularly spinulose.
In humid state the leaves are slightly tufted at the ends of the stems. They are somewhat squarrose turned down. In dry state, they are blackish and turned around the stem. The edge of the leaf is slightly rolled downward from the base to the tip of the leaf.
It is a dioicous species, which only rarely forms sporogonia.
The species can be found practically worldwide in the moderated and subtropical latitudes.
The spathulate leaves of this leaves are broadly rounded, and the midrib end in or before the tip of the leaf. It is not excurrent as hyaline hair or mucro. The edge of the leave is narrowly rolled downward in the lower part of the leaf, what can be seen on the picture as narrow dark stripe. On the upper part of the leaves there are normally many round brood bodies. (Unfortunately they are too small, that one can see them on the very comprimated jpg-picture below.) The cells are in most cases rather regularly arranged in rows.
The plants reach hights of 3cm, in most cases 1-2cm. They are green until dark green. (The plant on the picture is soiled with some mud from the last flood, and the fresh green color can't be seen.) The leaves at the ends of the stems are clearly bigger and arranged a bit more densely, so the the plant is somewhat rosulate.
The seta of the plants of this species are reddish yellow. The teeth of the peristome are twisted 1-2times to the left. The cylindrical capsules are erect until horizontal.
The species can be found in Europe and North America. It grows on bark, concrete or sandstone near waters. In Europe it prefers the lower regions. It is frequent in the valleys of the great streams.