Key to species Field Collecting and Lab Observations Morphology
At the generic level Frullania is an exceedingly common liverwort in the southeastern United States. Mesic or frequently humid sites with adequate light often support large populations on trees. Several species occur on rock, and a few regional species may occur exceptionally as epiphylls on Rhododendon maximum. While the genus is easy to recognize by its dark coloration and leaf form, identifying species can be a challenge. Fortunately, the number of regional species is small in this otherwise diverse genus of 300-350 species worldwide (Gradstein and Meléndez 2011).
The number of Frullania species in the southeastern U.S. is 21 (Schuster 1992; Atwood 2017). Of these 21 species, 12 occur in the southern Appalachians. Six of the 21 are not known north of Florida. Frullania stylifera is reported for middle Tennessee, Arkansas, Missouri, Oklahoma, and Minnesota (Atwood 2016), F. donellii is limited to the southeastern Coastal Plain, and F. cobrensis is known from Florida, southern Georgia and northern Alabama (http://bryophyteportal.org/portal/). None of the Southern Appalachian species is globally rare but several species are of conservation concern at the state level. Given recent discoveries of significant range extensions for F. stylifera, F. appalachiana, and F. cobrensis, it seems reasonable to predict that additional species will be found in the southern Appalachians. Recommended references include John Atwood's forthcoming Frullania treatment in the Flora of North America series (FNA, vol. 29), and Schuster (1992). Schuster’s 1992 treatment of regional species is without parallel in the abundance of quality illustrations, extensive descriptions, and pages of interesting discussions; however, new species concepts for some taxa will appear in the FNA treatment (Atwood, 2017).
Identifications can be tricky due to inherent variability and a strong tendency for two or more species to occur closely admixed in the space of a few square millimeters. At first glance under the dissecting microscope, different species can appear remarkably similar making admixed species difficult to detect. It is common to find several species of Frullania on a single tree trunk upon which each species occurs within its own discrete patch while other occurrences on this same tree are admixtures of two or more species. Having the one-species patches helps to solidify one’s concepts making it easier to detect admixtures when they do occur. In addition, male plants in the Frullania appalachiana-eboracensis-virginica complex may be difficult to place to species. Female plants in these dioicous species are almost always present but may only be found if adequate material was collected.
Atwood, J. J. 2016. New stations for Frullania stylifera (Frullaniaceae) outside of the type locality. Evansia, 33(2), 96-101.
Atwood, J. J. 2017. Frullaniaceae. Bryophyte Flora of North America, Provisional Publication.
Gradstein, S.R. and Uribe Meléndez, J. (2011) A synopsis of the Frullaniaceae (Marchantiophyta) from Colombia. Caldasia 33: 367–396.
Schuster, R.M. 1992. The Hepaticae and Anthocerotae of North America East of the Hundredth Meridian. Volume V. Field Museum of Natural History, Chicago