Identification notes

This is a very rare plant with a highly restricted distribution and a very specialised habitat – around fluid filled knotholes in ancient trees, especially beech, known as dendrotelmata, and where water trickles intermittently down the trunk and exposed roots.

Originally included in the genus Zygodon, it does form small cushions on bark and has a similar habit, but the leaves are different. When dry they are spirally twisted but when moist it is clear that they are a much darker green and translucent rather than reflective because the cells are smooth, having no papillae, and therefore do not scatter the light as much as Zygodon leaves. Capsules are produced reasonably often and are pyriform rather than ovoid. Leaf gemmae are absent but gemmae are abundant on the persistent protonema.

Despite producing spores and gemmae freely, the plant remains stubbornly fastidious and is absent from most apparently suitable habitats.

Distribution in Great Britain and Ireland

It would be remarkable to find this plant outside of its known haunts in the New Forest, Burnham Beeches and Epping Forest.