Unraveling the Origin of Vittaria appalachiana, the "Appalachian Gametophyte"

Pinson, Jerald

Ferns and lycophytes are distinct among plants in producing two free-living life stages: a typically long-lived sporophyte phase and a usually short-lived gametophyte phase. Notably, however, about 10% of fern species are able to produce perennial, vegetatively-reproducing gametophytes. While most of these species are restricted to tropical habitats, the gametophytes of a few can be found growing in temperate regions. Occasionally, the temperate populations are able to produce sporophytes in situ. More commonly sporophytes are only produced in their corresponding tropical populations. In just one species—Vittaria appalachiana—are sporophytes completely unknown. Vittaria appalachiana reproduces asexually via the production of gemmae throughout its range in the Appalachian Mountains and its origin has long been a mystery. Previous studies have suggested it may be a hybrid between its two closest relatives. Through analyses of plastid and nuclear sequence data, this study demonstrates that a hybrid origin is unlikely, instead suggesting that this species diverged from within the Vittaria graminifolia lineage. Contains two records from GRSM.