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Lejeunea sharpii (Schust.) Schust.
Sharp's Pouncewort
Federal Protection: No US federal protection
State Protection: No Georgia state protection
Global Rank: G2G3
State Rank: S1?
Element Locations Tracked in Biotics: Yes
SWAP 2015 Species of Greatest Conservation Need (SGCN): No
SWAP 2025 Species of Greatest Conservation Need (SGCN): Yes
2025 SGCN Priority Tier: Highest Conservation Concern
Element Occurrences (EOs) in Georgia: 4
Habitat Summary for element in Georgia: Riparian zones on exposed dry to moist rock, usually limestone but also sandstone or dolomite
Small, leafy liverwort growing prostrate in patches generally of a few centimeters in extent. Individual shoots (leaves and stem) up to 1.3 mm wide. Leaves complicate-bilobed, the dorsal lobe rounded, lying flat and slightly overlapping adjacent leaf towards shoot apex. Underleaves bilobed. Plants when dry somewhat shiny.
Develops trigones and intermediate thickenings in the cell walls between leaf cells. Living cells possess numerous small, homogeneous, glistening oil bodies.
To the untrained eye Lejeunea sharpii is easily confused with other small leafy liverworts, e.g. Lejeunea spp., Leucolejeunea spp., Rectolejeunea maxonii, Radula spp, and Frullania spp. To the trained eye L. sharpii is nearly morphologically identical to L. cavifolia. Fortunately, the geographic ranges of L. sharpii and L. cavifolia apparently do not overlap. L. sharpii is endemic to the southeastern U.S. where it is rare in the Blue Ridge and more frequent in the Cumberland Plateau. Lejeunea cavifolia is a widely distributed northern hemisphere species whose range extends to the Arctic Circle and in the southeastern U.S. is generally restricted to higher elevations of the Blue Ridge. As stated by Schuster who named L. sharpii as a new species (1980, p 994), “L. sharpii must be separated with care from L. cavifolia.” Both species possess numerous, small glistening oil bodies in the cytoplasm of living leaf cells. Notable differences between the two species as pointed out by Schuster include: 1) underleaves of L. sharpii “rounded to subcordate at base on main stems” vs. “never subcordate at base” in L. cavifolia; 2) size of cells along the margin of the leaf lobe (1)15-17(19) microns in L. sharpii and (18.5)20-24(26) microns in L. cavifolia; and 3) gynoecial branch usually born on a short side branch in L. sharpii and gynoecial branch usually born on a leading branch in L. cavifolia. To this I would add (as described but not discussed by Schuster, 1980) that the leaves of L. sharpii are “nearly flat” while those of L. cavifolia are “convex.” This distinction is quickly evident when whole plants are magnified from above.
Lejeunea sharpii occurs on both limestone and sandstone outcrops as well as on the bark of hardwood trees. It occurs directly on bare rock or on the thin layer of soil (flow dirt) that accumulates over vertical rock surfaces. Flow dirt consists of soil particles deposited by flowing rain water. In addition, Lejeunea sharpii it is a frequent epiphyte growing upon older portions of mosses (e.g. Anomodon) growing over rock or tree bark. As is true for many other liverworts, Lejeunea sharpii requires habitats characterized by high humidity. In Georgia, Lejeunea sharpii grows in close association with other bryophytes including the hepatics, Cololejeunea minutissima, Cololejeunea ornata, Frullania sp., Lejeunea blomquistii, Radula australis, Radula mollis, Rectolejeunea maxonii, Metzgeria sp., Plagiochila parvifolia (=P. yokogurensis), P. undata, Porella platyphylla, and the mosses Anomodon attenuatus, A. rostratus, Fissidens dubius, Palamocladium leskeiodes, Schwetschkeopis fabronia, and Thamnobryum alleghaniense.
Lejeunea sharpii is a monoicous species and is apparently self-fertile. Perianths containing developing sporophytes occur in April and May and mature capsules just beginning to release spores were observed August 4 (2010) from Pigeon Mountain, Walker County, Ga. (pgd records). From the three specimens known at the time, Schuster (1980) describes L. sharpii as “abundantly fertile,” yet he fails to mention any sporophyte production or date of spore release.
Limestone outcroppings, sandstone outcroppings in areas where limestone occurs nearby, Cumberland, and ridge and valley.
Rutherford and Knox Counties, Tennessee (Schuster 1980). Herbarium records of Paul G. Davison extend the range into the Highland Rim section of the Interior Low Plateaus and the Valley and Ridge province of Alabama and the Cumberland Plateau of the Appalachian Plateaus province of Alabama, Georgia, and Tennessee.
Loss of habitat.
| Threat 1 | Threat 2 | Threat 3 | |
|---|---|---|---|
| General Threat | Climate change & severe weather | None | None |
| Specific Threat | Temperature extremes | None | None |
Protection of habitat, i.e. no removal of overstory forest; no disturbance to rocks on which the plants live. Boulders and rock outcrops along bluff lines should not be altered by repositioning them for decorative function. Fortunately, people (hikers, etc.) usually do not tamper with bryophytes found in rock crevices and on rock faces. Exceptions may occur where trails follow closely rock bluffs and native rock is used as a hand-brace by hikers. Other potential disturbances include pit fires from backwoods campers.
Schuster, R. M. 1980. The Hepaticae and Anthocerotae of North America, East of the Hundredth Meridian, Vol. 4. Columbia University Press: New York.
Paul G. Davison
September 2010