Trematodon Michaux, 1803.

Trematodon is a moderately large genus widely distributed throughout the world. However, it has only recently been found in California. Trematodon boasii was first found on Vancouver Island in British Columbia but it has recently been discovered at high elevations in the Central Oregon Cascades. It is a plant of moist soil in high montane and alpine regions. It is so small that it is unlikely to be collected except when sporophytes are present. The sporophytes are rigidly erect with a hypophysis somewhat longer than the urn. The gametophyte has leaves about 2 mm long with a strongly defined subula above a clasping and broadened leaf base.
see key to Bruchia Etc.

Species included:
Trematodon boasii W. B. Schofield