Jungermannia atrovirens
| Common Name | Dark Green Flapwort |
| Frequency | Infrequent |
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Distinguishing Features
Presenting on calcareous rocks along rivers and creeks, this inconspicuous dark green, simple leafy liverwort is loosely appressed to its substrate and spends significant portions of its year submerged in flowing water. The simple, spreading ovate leaves occur on irregularly-branched shoots up to 2mm wide undergirded by a tangle of dense, colourless rhizoids. Underleaves are lacking, but developing archegonia and antheridia are frequent and can be found on separate plants (“dioicous”). The modified leaves that surround the archegonia (“perianth”) form a characteristic ovoid sheath with a plicate or ribbed apex (see photo).
Similar species
This is a very generic looking liverwort, but it can be distinguished from other similar species by its habitat, lack of underleaves, rhizoids and reproductive characters. Relatively few species of liverworts have unlobed, simple leaves AND live the semi-aquatic, rock-bound life that J. atrovirens partakes in. Of those, species of Nardia, Chiloscyphus and Odontoschisma have obvious underleaves that can be seen with a hand lens. The remaining lookalikes are all within the group of taxa that have at one time or another been part of the genus Jungermannia. Jungermannia exsertifolia is restricted to subalpine drainage banks and has equidimensional leaves on shoots that are 2.5 mm or wider, whereas shoots of J. atrovirens are less than 2 mm wide and bear leaves that are longer than they are wide. Plectocolea obovata and P. hattoriana are also found on siliceous rocks in streams, but both have bright red-purple rhizoids, whereas those of J. atrovirens are colourless. Solenostoma confertissimum is very similar in size and habitat, but its leaves are about as wide as they are long, whereas J. atrovirens has leaves that are longer than wide. Jungermannia pumila is identical in size, shape and semiaquatic lifestyle, but it grows on siliceous rocks and has antheridia and archegonia on the same individual plants. Jungermania borealis is almost identical in form but with leafy shoots closer to 1 mm (as opposed to 2 mm in J. atrovirens) and an arctic-alpine distribution.
Habitat
Moist to mesic, often calcareous rock outcrops, cliffs, ledges, crevices, boulders, humus, streambanks, heath, tundra, and occasionally decayed wood in the lowland, montane, and subalpine zones
Associated species
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Distribution Map
Relevant Literature
- Godfrey, J.D. (1977). Hepaticae and Anthocerotae of southwestern British Columbia . [Doctoral dissertation, University of British Columbia]. UBC cIRcle.
- Hong, W. S. (2007). Scapania. In Flora of North America Editorial Committee (Eds.), Flora of North America North of Mexico (Vol. 3) . Oxford University Press.
- Wagner, D. H. (2013). Guide to the liverworts of Oregon: Scapania undulata . Oregon State University Herbarium.