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Pohlia rabunbaldensis A.J. Shaw
Rabun Bald Feathermoss
Federal Protection: No US federal protection
State Protection: No Georgia state protection
Global Rank: G1
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: Highest Conservation Concern
Element Occurrences (EOs) in Georgia: 1
Habitat Summary for element in Georgia: Rocky, moist openings, select high balds
Pohlia rabunbaldensis is a relatively small moss with slender shoots (stems with leaves) reaching ca. 1 cm in length. The stems are mostly unbranched and support leaves that are noticeably spirally arranged. The leaves are lanceolate, 08. – 1.4 mm long, with a strong costa extending nearly to the leaf apex. Leaf bases are decurrent and leaf tips are serrulate. Occasional occurrence of gemmae (bulbils) borne singly in leaf axils. Gemmae are firm, swollen, and bear lamellate leaf primordia (see illustrations). Gemmae were light green to slightly yellowish in August and apparently age to an orange to reddish color by autumn.
Pohlia rabunbaldensis is similar to P. drummondii, a species found in western and northeastern North America, Europe, and elsewhere. Pohlia rabundaldensis differs from P. drummondii in that the latter has less prominent leaf decurrencies, and mature gemmae are a “characteristic red color” (mature gemmae are “orange, orange-yellow, to reddish” in P. rabunbaldensis). Apparently, when dry material is compared, P. drummondii lacks the dull color and contorted leaves possessed by P. rabunbaldensis. These latter characters are shared with P. annotina, a species that may co-occur with P. rabunbaldensis. Pohlia annotina, which also has decurrent leaves, differs in its “vermicular gemmae with apical, peglike leaf primordia” (see illustrations). Small populations of P. rabunbaldensis in which gemmiparous shoots are seemingly absent, or populations seen early in the growing season in which gemmae are not yet developed, may be unidentifiable.
Pohlia rabunbaldensis occurs on mineral soil and rock in montane habitats. Given its occurrence on soil of a manmade trail water bar, it is able to disperse locally at least to some extent. Gemmae may be important as local perennating devices providing a means of survival over winter, but this is conjecture. To what extent shoots die back in winter is undetermined. Reproduction is apparently entirely asexual as sporophytes and male plants are unknown.
Pohlia rabunbaldensis is known from Rabun Bald Cliffs (presumably where the Federally listed lichen Cetradonia linearis occurs) from at least one collection cited by the naming author. Otherwise it is noted to occur along a trail in a northern hardwood forest dominated by Quercus rubra (Rabun Bald, GA) and along the Blue Ridge Parkway in a northern hardwood forest dominated Quercus rubra with Picea rubra (Snowball Mountian, NC). At Rabun Bald the following woody plants were noted along the trail in close proximity to P. rabunbaldensis: Acer rubrum, Betula sp., Clethra, Hamamelis virginiana, Kalmia latifolia, Quercus alba, Quercus prinus, Quercus rubra, and Rhododendron maximum. Bryophytes found within a few centimeters of P. rabunbaldensis at Rabun Bald included: Liverworts: Calypogeia sp., Cephalozia bicuspidata, Diplophyllum apiculatum, Jungermannia gracillima, Scapania nemorea. Mosses: Atrichum sp., Diphyscium foliosum, Ditrichum sp., Isopterygium elegans Pohlia annotina, Pohlia nutans, Rhizomnium punctatum, and Thuidium sp.
Along trails and cliffs above 4000 ft. in elevation. The extent of occurrence along the north facing cliffs below the summit of Rabun Bald has not been determined.
Pohlia rabunbaldensis is known only from Rabun Bald, Georgia and from a second location ca. 70 air miles to the NE along the Blue Ridge Parkway at Snowball Mountain in Buncombe County, NC.
Loss of habitat.
| Threat 1 | Threat 2 | Threat 3 | |
|---|---|---|---|
| General Threat | Climate change & severe weather | None | None |
| Specific Threat | Temperature extremes | None | None |
Shevock, J. R., and A. J. Shaw. 2005. Pohlia robertsonii and P. rabunbaldensis (Bryopsida, Mniaceae), Two New Species from the Western and Eastern United States. The Bryologist 108: 177 – 182.
Paul G. Davison
September 2010