Guide to Liverworts of Oregon: Scapania americana K. Muell.
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Scapania 1 oil bodies several per cell > Scapania 2b marginal teeth evenly spaced or lacking > Scapania 3a dorsal lobe decurrent > Scapania 4a keel hardly curved > Scapania americana
Synonym: Scapania bolanderi var. americana (K. Muell.) Frye et Clark
Special Status: None.
Recognition: Distinguished by the finely, evenly dentate leaf margins contrast with S. bolanderi (which has dentition different on dorsal vs. ventral lobe) coupled with the decurrent base of both dorsal and ventral lobes. The decurrent wing of the dorsal lobe is usually folded and lacerate on the most fully developed leaves of a shoot. The term "ampliate" applies to this condition. The preference for inorganic. substrates--rock or sand--is also an important distinguishing feature.
Distribution: On rocks with seasonal sheet drainage, or on sand in coastal strip; widespread in western Oregon from lowlands to about 5000 feet, scarce higher.
Comments: I have seen this on alders and bigleaf maples in narrow valley bottoms of the coast range, so its fidelity to rock substrates is not absolute.
Scapania americana. Lane County, Oregon.
Scapania americana. Male bract.
Scapania americana. Lane County, Oregon.
Scapania americana. Lane County, Oregon.
Left: Sweet Creek, Lane Co., Oregon. DHW 1247. Right: Waldo Lake, Lane Co., Oregon. DHW m0765fb.