Plants epiphytic. Sporophytes absent in flora. Gametophytes much branched. Gemmae tapering at ends, end cells not swollen; body cells 4, rhizoid primordia on each end cell.
Habitat: Epiphytic in dark, moist hollows formed by flaring root buttresses of beech (Fagus grandifolia Ehrhart)
Elevation: 0–50 m
La., Mexico, West Indies, Central America, South America.
Louisiana plants, known only from St. Helena Parish, are identical to gametophytes grown from sporophyte plants from Central America both morphologically and in starch gel enzyme electrophoresis patterns. Gametophyte colonies and possibly sporophytes of Vittaria graminifolia should be expected in similar habitats at additional sites along the Gulf Coast and in peninsular Florida. Sporophytes of V. graminifolia differ from those of V. lineata in having trilete spores, dilated terminal cells of the soral paraphyses, stem scales with acute (not long filiform) apices, and a chromosome number of 2n = 60. Earlier reports of sporophytes of V. graminifolia in Florida (as V. filifolia) have been shown to refer to aberrant forms of V. lineata (G. J. Gastony 1980).