The gametophyte phase of ferns plays an important role in habitat selection, dispersal, adaptation and evolution, but species identification of free-living gametophytes is difficult. Chen et al. use a combination of distance-based and tree-based approaches to evaluate the discriminating power of three candidate barcodes, matK, rbcL and trnL-F, for sporophytes of 16 vittarioid ferns, and generate sequences of the trnL-F region from 15 gametophyte populations by tissue-direct PCR. They find that whilst success rates for matk and rbcL are low, results for trnL-F show good primer universality, sequence quality and species discrimination, and it is thus recommended for identification of gametophytes in the field.
