Family: Polytrichaceae Order: Polytrichales(de)
The plants of this genus are at first sight not very similar to those of the genus Polytrichum. Their lingulate until lanceolate leaves are bordered by distinct, elongate cells and are -at least at the tip- serrate. They are not sheathing the stem, as it is the case in Polytrichum species, and the midrib is thin and doesn't fill nearly the whole leaf. The cells are rounded or hexagonal. Frequently there are also teeth on the underside of the leaves blades.
The capsules, which sit on long setae, are in most cases cylindrical. The operculum is long rostrate, and the calyptra is hood-shaped.
In total there are 15 species, of which 5 can be found in Europe.
As the name tells, the leaves of this species are clearly undulate. The edge of the leaves is serrate from the tip down to the base, often with double teeth.
The plants are robust, in most cases 3-6cm high, and with about 1cm long leaves. They form loose cushions and are very frequent in all kind of forests, especially on loamy soils.