Schistidium is a genus of small, dark‑green plants nearly always found on bare rock. The genus typically has short, erect (sometimes hyaline‑pointed) leaves, short, broad, immersed capsules and well‑formed, haplolepidous peristome teeth. Schistidium and Grimmia have identical gametophytes and are sometimes treated as a single genus. Schistidium differs from Grimmia in having systylius capsules, greatly enlarged perichaetial leaves and poorly developed stomata. Systylius capsules have evolved several times in the mosses but their function is unknown. Bremer (1981) suggested the feature enhanced spore dispersal by carrying large numbers of spores along with the columella when the operculum was detached. Alternatively, the advantages of this structure may lie in the fact that the capsules remain only partially open for some time after dehiscence. This may be beneficial in reducing desiccation and in limiting spore dispersal to times of more optimal conditions for the establishment and germination of spores, i.e., during the period between wetting and drying when the peristome teeth undergo hygroscopic motion.

The presence of small, non‑plicate calyptrae separate Grimmia and Schistidium from the rest of the Grimmiaceae. The calyptra can be mitrate or cucullate, but the distinctions between these two types of calyptra in Schistidium are minor and in fact both types can be found within single species or even single collections.