Guide to Liverworts of Oregon: Aneura pinguis (L.) Dum.
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<1a plants thallose > 2b chloroplasts numerous > 62a thallus tissue homogeneous > 63b thallus ribbon like > 65b ventral scales absent > 66b thallus without hairs > 67a sex organs on branches > 68a Thallus 3-10+ mm wide >Aneura
Synonym: None
Special status: None
Recognition: It varies greatly in size, from the ditch plants illustrated below to narrow, bog forms. Ruffly ribbons with a poorly defined midrib are the key character for this species at low elevations. The closest lookalikes are species of Pellia, from which it differs in having fewer oilbodies and smaller cells (Aneura epidermal cells <100 μm long, Pellia cells more than 100 μm long). The smaller forms resembles species of Phaeoceros, from which they differ in having numerous chloroplasts in each cell.
Distribution: Grows in bogs or on peaty muck in wet sites, often inundated for all or part of the year. Widespread, from low to high elevations.
Comments: Although reputed to be a calciphile, and indeed abundant where limy deposits are found in streams, it seems just as happy in ditches in our acid forest soils. Many of the low elevation popuations consist of large, robust plants quite different from the small, worm like plants of montane bogs. Current literature (Nelson, J.B., and P.G. Davison. 2004.) recognizes larger plants are distinct and use Aneura maxima (Schiffn.)Steph. for this species. The Santiam River Valley and Goodman Creek material illustrate an example of this form. The Sutton Beach material is of a very different kind of plant.
Stotler and Crandall-Stotler (2017) cite a study showing A. maxima is restricted to Europe and referred all North American records to A. sharpii. However, they list Aneura sharpii as occurring in eastern North America only, which leaves the large form of the West pending further study to clarify taxonomy and nomenclature. David Long (in litt.) has suggested there is a large complex of temperate species, none of which match plants from the type locality of A. maxima in SE Asia.
Santiam River Valley, Linn Co., Oregon. DHW m1289.
Thallus margin. Goodman Creek, Lane Co., Oregon. DHW m1779.
Cells with oil bodies. Goodman Creek, Lane Co., Oregon. DHW m1779.
Middle thallus section. Goodman Creek, Lane Co., Oregon. DHW m1779.
Gynoecium indicated. Sutton Beach, Lane Co., Oregon. DHW m2413.
Cross section through archegonial cluster. Sutton Beach, Lane Co., Oregon. DHW m2413.
Marginal cells with oil bodies. Sutton Beach, Lane Co., Oregon. DHW m2413.
Young calyptra with developing sporophyte within. Sutton Beach, Lane Co., Oregon. DHW m2413.
Cross section of young calyptra with sporophyte embryo. Sutton Beach, Lane Co., Oregon. DHW m2413.