Marsupella paroica R.M. Schust.
Family: Gymnomitriaceae
Synonyms
none
NatureServe Conservation Status
G3
Distribution
Endemic to North America. Canada. Ontario. U.S.A. Georgia, Kentucky, Michigan (portal), Minnesota, North Carolina, South Carolina, Tennessee, Virginia. (Davison and Risk 1992; Schuster 1957, 1974). Mexico. (Váňa et al. 2010).
Habitat
Regionally occurring on shaded rock (wet to rather dry) at the higher elevations (generally 3600 ft and above) in northern hardwood forests and in spruce-fir forests. Also, more rarely at lower elevations (ca. 2500 ft) in the Blue Ridge escarpment gorges. Often found near streams but not typically on wet rocks subject to frequent innundation.
Brief Description and Tips for Identification
Shoots green to brown, usually growing erect and close to one another forming loose cushions 1 cm in diameter or, more often, covering much larger areas of rock substrate. Individual shoots up to 1.5 cm tall, usually smaller, and less than 2 mm wide. Leaves inserted transversely, bilobed, the two lobes usually unequal in size. Leaf margin towards the base of the leaf reflexed (best seen on the leaf margin that inserts on the dorsal side of the stem).
Paroicous, antheridia located in bracts below the perianth. Perianth short, not readily evident, overtopped by the female bracts.
The regional species of Marsupella are characterized by bilobed leaves transversely inserted on the stem and mostly two oil bodies per leaf cell. M. paroica is the only monoicous (paroicous) species of the genus in the Southern Appalachians (other regional species are dioicous). Successful demonstration of the paroicous condition is key to positive identification. Vegetatively, M. paroica is very similar to small forms of M. emarginata, a very common species. Both share the narrowly reflexed leaf margin towards the leaf base. The leaf margin is plane throughout in M. sphacelata and M. funckii. M. sphacelata is a widespread species occurring regionally along seepages of exposed rock outcrops. M. funckii is regionally known only from high elevation cliffs in the Great Smoky Mountains National Park, Tennessee.
Salient Features
- Paroicous, antheridia occurring in leaf axils just below the perianth
- Leaf margin, in part, reflexed
- Oil bodies often 2 per cell in cells of the leaf as in other regional Marsupella
References
Davison, P. G., and Risk, A. C. 1992. Hepatics of Bad Branch Nature Preserve, Letcher County, Kentucky. Evansia, 9, 52-55.
Schuster, R. M. 1957. Notes on Nearctic Hepaticae. XII. Marsupella paroica n. sp. The Bryologist, 60(2), 145-151.
Schuster, R.M. 1974. The Hepaticae and Anthocerotae of North America East of the Hundredth Meridian. Volume III. Columbia University Press, New York
Váňa, J., Söderström, L., Hagborg, A., von Konrat, M. and Engel, J.J. 2010. Early Land Plants Today: Taxonomy, systematics and nomenclature of Gymnomitriaceae. Phytotaxa 11: 1–80.
Habitat
Marsupella paroica
Near the summit of Roan Mtn., on relatively dry rock but restricted to near the surface of the soil where moisture is held for more prolonged periods.
Marsupella paroica
Rather wet rocks occurring with Scapania nemorea and other bryophytes on a steep, north facing slope below a ridge crest in a northern hardwood forest, 3600 ft, Lambert Mtn., Macon Co., N.C.
Habitat
Marsupella paroica
Sloping face of moist rock near summit of Roan Mountain, Tennessee.
Marsupella paroica
On the face of low outcrop in a northern hardwood forest in North Carolina
Habit
Marsupella paroica
With dehisced capsules on 9 May 2018, Roan Mtn.
Marsupella paroica
The reflexed leaf margin is well developed in several shoots in the above photo.
Marsupella paroica
At times small and scrappy, yet fertile and demonstrably paroicous.
Habit
Marsupella paroica
With freshly exserted capsules, 10 May 2018, near summit of Roan Mtn.
Morphology
Marsupella paroica
The inset photo illustrates a dehisced antheridium. Careful dissections to remove male bracts may be required to demonstrate these delicate, post-mature gametangia.
Marsupella paroica
The previous photo with post-mature antheridium, and seta of mature sporophyte visible, is from material collected the same day and from same population as the material shown above possessing nearly mature gametangia. Presumably, sporophytes are conceived in spring and develop through the summer and winter months before releasing spores the following spring. The paroicous condition should be confirmed for confident identification.
Marsupella paroica
The left most shoot is fertile. Male bracts (at least two pairs shown above) have saccate bases. The apex of the perianth is just visible between the overtopping female bracts. The saccate base of male bracts is not always pronounced. One should always confirm the presence of antheridia or remnant antheridial stalks with a compound microscope after dissection.
Morphology
Marsupella paroica
The narrowly recurved leaf margin as seen in the lower three pairs of leaves of the plant in the middle photo is a critical feature shared with the more common Marsupella emarginata. Notice that the development of this recurved leaf margin is not consistently well-formed as it is essentially absent in the left-most plant, at least on the side of the plant photographed; the reverse side may show better development of this character.
Marsupella paroica
The tedious dissection to remove whole leaves reveals that most leaves are unequally bilobed, a character not generally associated with M. emarginata. Small forms of M. emarginata are very similar to M. paroica as discussed in Schuster (1974).
Marsupella paroica
Oil body number in leaf cells is frequently 2 per cell as in most Marsupella species. Yet, as shown above there can be a high percentage of cells with 3 oil bodies.
Similar Taxa
Marsupella emarginata
Capable of becoming a much larger plant than M. paroica, M. emarginata is dioicous with a wider ecological tolerance including the ability to thrive where more frequently submerged in water or long exposed to direct sunlight.
Marsupella sphacelata, sensu Schuster 1974
A dioicous species not likely to be confused with M. paroica due to the more rounded leaf lobes and leaf margins that are never reflexed.