Phylogeny of Aspleniaceae inferred from rbcL nucleotide sequences

We determined rbcL sequences of 25 species and 2 varieties of Aspleniaceae with various leaf and rhizome morphologies, and conducted a phylogenetic an alyses with the following conclusions: I) leaf shape is not congruent with rbcL phylogeny in Aspleniaceae; 2) rhizome morphology (erect-ascending or c reeping) reflects rbcL phylogeny; 3) naturally occurring hybrids are genera ted only between closely related species and thus reflect the rbcL phylogen y. The third conclusion was especially well-supported by our allozyme analy ses of hypothesized hybrids between distantly related species of Aspleniace ae. A popular cultivated fern hybrid in Japan, Asplenium x kenzoi, is belie ved to be a hybrid between A. prolongatum and A. wrightii, which are distan tly related in our molecular tree. However, our allozyme analysis of A. x k enzoi showed that it is a hybrid between A. antiquum and A. prolongatum, wh ose close relationship was first suggested by our rbcL tree. Thus, A. x ken zoi appears to to be a hybrid between two closely related species with Very different morphologies.