Loading profile. Please wait . . .
Plagiochila caduciloba Blomquist
Gorge Leafy Liverwort
Federal Protection: No US federal protection
State Protection: No Georgia state protection
Global Rank: G3
State Rank: S1?
Element Locations Tracked in Biotics: Yes
SWAP 2015 Species of Greatest Conservation Need (SGCN): Yes
SWAP 2025 Species of Greatest Conservation Need (SGCN): Yes
2025 SGCN Priority Tier: High Conservation Concern
Element Occurrences (EOs) in Georgia: 6
Habitat Summary for element in Georgia: Moist cliff faces
Plagiochila caduciloba is a moderately small leafy liverwort with erect, aerial shoots arising from horizontal shoots that lie against the substratum. Aerial shoots (leaves and stems) are ca. 0.5 – 2 mm wide and 0.5 – 2 cm long. Underleaves minute, consisting of 1-2 lobes, each lobe a single series of cells. Lateral leaves are bilobed, each lobe bearing several ramifications that are of a fragile nature and quite prone to breaking off. Shoots may bear leaves in which the ramifications and lobes have all broken away leaving then only truncated, unlobed leaves attached to the stem. In living material, 9-14 homogeneous oil bodies occur in the cytoplasm of leaf cells. Male plants are unknown. Sterile female shoots bearing perianths with archegonia are occasional, otherwise plants are without sexual structures.
Given the distinctive leaf ramifications Plagiochila caduciloba is not likely to be confused with any other North American species. Poorly developed material consisting of depauperate shoots with bilobed leaves largely lacking in ramifications may resemble the regionally rarer, Fraser fir forest inhabitant Plagiochila exigua (=P. corniculata) or small expressions of the often consociated P. austini.
Plagichila caduciloba typically occurs on shaded, damp rock faces usually in close proximity to running water in Canadian hemlock-cove hardwood forests with an understory of Rhododendron maximum in steep terrain. At waterfalls it may occur in protected rock recesses behind and beyond the abrasion of the curtain of falling water. Further from the water, it may occur under the protected ledges of cliff bases or large boulders. More rarely it occurs on bark of trees (Betula alleghaniensis and Ilex opaca) or shrubs (Rhododendron maximum and R. minus) in stream ravines. While it may occur in dense, pure patches of several square centimeters, more typically it grows with aerial shoots widely separated, intermixed with other liverworts, and thinly scattered over the substrate. The species ranges in elevation from ca. 1500 – 6000 ft. Frequently associated species include the independent fern gametophytes Vittaria appalachiana and Hymenophyllum tayloriae, and the following liverworts: Bazzania denudata, Blepharostoma trichophyllum, Harpalejeunea ovata, Herbertus aduncus, Lejeunea laetevirens, L. lamacerina subsp. geminata, Plagiochila austini, Plagiochila retrorsa (=P. sharpii), P. virginica, Radula obconica, R. sullivantii, and R. tenax.
Reproduction is purely asexual by local spread of caducous leaf lobes that serve as vegetative propagules.
Blue Ridge stream ravines and areas with shaded rock outcrops with protected rock shelters. Shaded, rocky ravines near mountain summits in the Blue Ridge. The population(s?) at the “Canyon at Tallulah Falls” has apparently not been seen since 1893. Verification of continued existence in Tallulah gorge is warranted given the site’s significance as the southernmost on record.
Endemic to the Appalachians, primarily in the Blue Ridge of the southern Appalachians with an outlying population to the north in the Cumberland Mountain section of the Appalachian Plateaus province in Kentucky (Letcher Co.). Georgia (Rabun Co.), North Carolina (Clay, Burke, Graham, Haywood, Jackson, Macon, Swain, Transylvania Cos.), South Carolina (Oconee and Pickens Cos.), and Tennessee (Blount, Monroe, and Sevier Cos.).
Loss of habitat.
| Threat 1 | Threat 2 | Threat 3 | |
|---|---|---|---|
| General Threat | Climate change & severe weather | None | None |
| Specific Threat | Temperature extremes | None | None |
Historically, Plagiochila caduciloba was collected in the canyon at Tallulah Falls in 1893 by J.K. Small. The canyon lies at the boundary of Rabun and Habersham counties and the specimen (NY) is attributed to Habersham Co. Otherwise the species was locally frequent in 1994 & 1995 above and below the High Falls on Big Creek, 2000-2200 ft in elevation W of HWY 28, and seen to the east of HWY 28, on Big Creek, elev. 2300 ft. in 1994 (all in Rabun Co., personal observations, specimens in UNAF). The remaining known locations in Georgia are also in Rabun Co. (arranged south to north): 1) bank of Chattooga River, 1/8 mi NE of bridge on US 76 (1995, Anderson 27348, DUKE); 2) Reed Creek Falls, just south of Persimmon Gap (1995, Zartman 452, DUKE); 3) along Chattooga River ca. 1 mi. south of Ellicott Rock, 34.98222 N, 83.10715 W (2007, Kauffman 45g, 46b, UNAF). Presumably these populations are stable but may warrant relocating to confirm continued existence in the face of forest change with the death of Canadian hemlock due to adelgid infestation.
Protection of habitat.
Davison, P.G. and A.C. Risk. 1992. Hepatics of Bad Branch Nature Preserve, Letcher County, Kentucky. Evansia 9:52-55.
Groth, H., G. Helms and J. Heinrichs. 2002. The systematic status of Plagiochila sects. Bidentes Carl and Caducilobae Inoue (Hepaticae) inferred from nrDNA ITS sequences. Taxon 51: 675—684.
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