Relationships within the Appalachian Asplenium polyploid complex have been well characterized using morphology, cytology, chromatography and isozymes. The complex consists of the diploids A. rhizophyllum, A. platyneuron, A. montanum and their six hybrids. However, the maternal origins of the hybrids are unknown. Non-coding regions of the maternally-inherited chloroplast genome, such as the trnL-F spacer region, can be used to reconfirm hypothesized progenitors and to hypothesize the direction of the crosses. For example, cleaved amplified polymorphic sequence (CAPS) analysis of the trnL-F region indicates that A. rhizophyllum contributed the chloroplast genome to the only known natural fertile population of the allopolyploid A. ebenoides, with A. platyneuron presumably serving as the paternal parent. Our maternity finding concurs with Slosson's limited laboratory experimentation in synthesizing A. ebenoides, and shows that using trnL-F to determine maternity in these crosses is an accurate technique. The internal transcribed spacer region of the nuclear ribosomal repeat (nrDNA ITS) has not often been used in fern molecular systematics, due at least in part to within individual heterogeneity. We are studying this gene region in the Appalachian Asplenium complex not only because of its potential as a biparental marker for phylogeny reconstruction, but also to determine whether allopolyploids exhibit nucleolar dominance.

Key words: allopolyploid, Asplenium, nrDNA ITS, nucleolar dominance, trnL-F