2010 Volume 60 Issue 3 Pages 131-140
Using plastid trnK, trnL and trnL-F sequences and nuclear ITS sequences (4558 bp in total) from 32 individuals of 13 species, we conducted a combined analysis to clarify phylogenetic relationships of the species of Tofieldia and Triantha and to discover new taxonomic characters. According to strict consensus of 45 most parsimonious trees, the two genera are monophyletic with 100% bootstrap support. In Tofieldia, three robust clades (100%) are formed: (1) To. coccinea, To. nuda, To. divergens, To. yunnanensis and To. thibetica, (2) To. calyculata, and (3) To. okuboi, To. glahra and To. pusilla. The species of the clade 3 are primarily characterized by a broad and sharply bent leaf apex as in some species of Triantha. In clade 1, the Chinese species of To. divergens, To. yunnanensis and To. thibetica are grouped (100%). They share long needle-like or hair-like processes on the leaf margin. In Triantha, two clades are formed: (1) Tr. japonica, Tr. occidentalis and Tr. glutinosa from the USA (76%), and (2) Tr. racemosa and Tr. glutinosa from Canada (91%). This might suggest that Tr. glutinosa is the assemblage retaining ancestral character states of Triantha and should be divided at least into two species in the future treatments.
