Rhytidium rugosum is the only species of the genus and the family.
It is a rather robust moss with stems up to 10cm long. It is yellowish or in most cases brownish green. Not only the leaves are unilateral, but the tips of the stems and the branches too are bent down, what can be seen clearly on the picture.
The leaves are ovate and longly acuminate. The tip of the leaf is serrulate. The cells are prosenchymatic, only the alar cells are quadratic or rectangular. The cells are papillose on the upper side. The midrib ends in the middle of the leaf.
The capsule is arcuate. The peristome consists of two rows of teeth. The operculum is conical and obliquely beaked(???). But mosses with capsules are rather rare.
Rhytidium rugosum can be found in europe and north america on more or less sunny, stony slopes, in particular on calciferous stones and on basalt, but is not frequent. In germany the species is endangered.