Marsupella emarginata
| Common Name | Notched Rustwort |
| Frequency | Frequent |
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Distinguishing Features
A common sight around wet rocks, the golden-green to red shoots of M. emarginata have leaves with the unmistakable shape of Mickey Mouse Ears when examined with a hand lens. The shoots don’t show much in the way of branching and can be quite variable in size, ranging from .5-2.5 mm wide and 1-5 cm long. The leaves are about as wide as they are long, bilobed (or shallowly notched, depending on your perspective) and have a sinus that descends to about one-quarter of the leaf’s length. The margins of the leaf are curled down (“recurved”) and the leaves as a whole diverge from the stem almost at 90 degree angles.
Similar species
Species of Anastrophyllum and Sphenolobus can have leaves of similar form and orientation, but in those genera, the leaves are slightly asymmetrical and tend to orient themselves towards one side of the stem, while in M. emarginata, the leaves are symmetrical and face upward. Among the species of Marsupella with wide spreading leaves, M. emarginata is likely to be mistaken only for M. aquatica, M. sphaecelata and M. sparsifolia. M. aquatica grows on rocks around fast flowing water and has been treated as a subspecies, differing in having a shallower sinus (less than 20% of leaf length) and leaves that are visibly wider than long. The predominantly subalpine M. sphacelata and M. sparsifolia have diverging, non-overlapping leaves like M. emarginata, but they also have a burnt purple-blackish colour that immediately distinguishes them.
Habitat
Moist to wet mineral soil, rock outcrops, cliffs, ledges, crevices, boulders, streambanks, and tundra, occasionally submerged in shallow water, in the lowland, montane, subalpine, and alpine zones
Associated species
Scapania americana, Nardia scalaris, Blindia acuta, Racomitrium aciculare
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.