Guide to Liverworts of Oregon: Gymnomitrion obtusum Lindb.
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Gymnomitrion 1a leaf margins crenulate, recurved Gymnomitrion obtusum
Synonyms: None.
Recognition: The small, julaceous stems are distinctinctive under the handlens. This species differs from the its closest look alikes in the genus by the slight recurvature of the leaf margins, the rounded, not apiculate, leaf lobe tips which are slightly crenulate. The leaf surface is roughened by small bumps. It has two oilbodies per cell.
Distribution: Grows on rock, mainly acidic rock, typically on north facing ridgetops. Common at middle elevations in the Cascades, less common in the Coastal Mountains but extending to low elevations a few miles inland from the coast.
Comments: The most common species in the genus. A number of specimens from our area have been reported as Gymnomitrion coralloides. All the specimens I have examined turned out to be Gymnomitrion obtusum. However, Gymnomitrion coralloides has recently been found in California so it should eventually turn up in Oregon. A photo of Gymnomitrion coralloides is given below. It differs from Gymnomitrion obtusum in having a smooth cuticle (vs. verrucose) and incurved leaf margins (vs. leaves recurved).
Gymnomitrion obtusum - Columbia River Gorge. Photo by John Davis, used with permission.
Gymnomitrion obtusum - Left: Golden Falls, Coos Co., Oregon. DHW m1603a. Right: Stone Chair Trail, Coos County, Oregon. DHW m0015a.
Here is a picture of Gymnomitrion coralloides Nees :
Gymnomitrion coralloides - Mt. Katahdin, Maine. R.M. Schuster 15816.