Plants in tufts or small turfs to 0.5 cm high, dark-green but with a glaucous cast due to the long awns, never glossy. Leaves spreading when moist but deeply keeled and crispate when dry, oblong to spatulate, to 2.5 mm long, 3–4: 1. Median laminal cells pluripapillose with papillae usually not C-shaped, to 15 µm broad, in straight rows, with lumen/wall ratio 3–4: 1, quadrate with rounded to angular lumens and small corner thickenings. Basal cells rectangular with straight lateral walls, to 20 µm broad, about 10: 1, smooth, thin-walled. Suprabasal median cells usually somewhat smaller, less papillose and thinner walled than adjacent laminal cells. Costa occupying about 1/8 of leaf base, gradually tapering and excurrent in an hyaline and smooth awn which may be more than 1/2 as long as the subtending lamina. Abaxial cells of costa narrowly rectangular, to 12 µm, 4–10: 1, smooth, not pitted on lateral walls. Adaxial cells of costa similar to the adjacent laminal cells. Costa cross-section about 2 times as broad as thick, with a strong dorsal stereid band, a single layer of guide cells, and with a well-developed ventral epidermis. Margin entire throughout, recurved to near the apex. Axillary hairs to 150 µm, to 10 cells long, with no basal brown cells. Rhizoids red-brown, to 20 µm wide at base, smooth and monopodially branched. Stem with central strand, rather thick-walled inner cortical cells and several rows of thicker walled, smaller outer cortical cells.
Dioicous. Perichaetial leaves little differentiated from vegetative leaves. Seta to 25 mm, red-brown, straight, smooth. Capsule erect or almost so, with the urn cylindric but slightly arcuate, to 3 mm, about 6: 1. Operculum conic-rostrate, 1/4–1/2 of urn length. Annulus differentiated but not revoluble. Peristome straight to slightly dextrorse, pale to pinkish, to 0.7 mm long, with almost no basal membrane, densely papillose throughout. Exothecial cells long rectangular (more than 10: 1) and thick-walled with lumen/wall ratio 1–2: 1, not in regular rows, to 15 µm wide. Spores to 10 µm, nearly smooth.
This moss is seldom found away from human habitation. It is almost cosmopolitan in cooler and humid zones of both hemispheres, and is very common on cement walls and on the mortar of brick walls in coastal California, especially north of the San Francisco Bay. Out of the fog zone of the coast it quickly disappears, but I have tentatively identified to this species a few plants from calcareous rocks in the deserts east of the Warner Mts. in Northeastern California. T. muralis may be identified by its small size, smooth but usually long awns on leaves which are recurved nearly to the apex. Its identity can usually be confirmed by looking for the rather cryptically differentiated pachydermous cells of the basal leaf margin.
![University of California [UC]](http://ucjeps.berkeley.edu/common/images/logo_uc_80.png){kind=logo}
