Guide to Liverworts of Oregon: Mannia gracilis (F. Weber) D. B. Schill & D.G. Long
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1a sex organs on primary thallus Asterella 2b monoicous; spores <100μm > Asterella 3b spores yellow > Mannia gracilis
Synonym: Asterella ludwigii (Schwaegr.) Underw., Asterella gracilis (Web.) Underw.
Special status: None.
Recognition: The globose carpocephala coupled with the reticulate-ridged, yellow spores are distinctive. The spores often have a distinctive nipple on the proximal face.
FNA description (Whittemore and Hicks 2023):
Thalli 5--12 x 1.5--3 mm, moderately or strongly incurved when dry, ventral branching rare, upper surface green or ± purplish, plane, underside ± purple, often blackish; epidermis persistent. Ventral scales ± purple, reaching about to thallus margin, with scattered hyaline oil-cells; appendages 1(--2) per scale, ± purple, broadly lanceolate or narrowly elliptical, 0.35--0.5 x 0.1--0.2 mm. Sexual condition paroicous. Antheridia in clusters immediately anterior to carpocephalum. Carpocephala on elongate thalli, stalk naked, disk flattened-hemispherical or low-conic, smooth, involucres obliquely spreading, pseudoperianth present. Spores yellow or brownish, 50--65 μm.
Distribution: On soil of ledges and crevices as well as open slopes at higher elevations; widespread, across the state from lowlands to the high mountains.
Comments: This is the most common species of the group in Oregon as a whole; Asterella (Calasterella) californica may be a bit more frequent in SW Oregon since it is characteristic of the California Floristic Province while this species is a member of the circumboreal flora.
This species, generally treated as an Asterella until 2010, when molecular analyses showed it could be transferred into the genus Mannia (Schill, Long, and Forrest 2010). Traditional taxonomic grouping that incorporates retention of ancestral morphological characters makes Asterella useful for generating visually intuitive identification keys.
Columbia River Gorge, Clark/Skamania County Line, Washington.
Cone Peak, Linn Co., Oregon.
Young thallus, Spencer Butte, Lane Co., Oregon. DHW m1492a.
High and median focus of spores, Elkhorn Ridge, Baker Co, Oregon. DHW 8191
China Wall ACEC, Coos Co, Oregon. J. Sperling B-20-JS-09. ORE.
China Wall ACEC, Coos Co, Oregon. J. Sperling B-20-JS-09. ORE.
Operculum. China Wall ACEC, Coos Co, Oregon. J. Sperling B-20-JS-09. ORE.
Distal aspect. Calif., Mariposa Co., Yosemite National Park, along trail to Cathedral Lake, Doyle 3252 (UC).
Proximal aspect. Calif., Mariposa Co., Yosemite National Park, along trail to Cathedral Lake, Doyle 3252 (UC).
Side view. Calif., Mariposa Co., Yosemite National Park, along trail to Cathedral Lake, Doyle 3252 (UC).