Sequences from the internal transcribed spacer (ITS) of the nuclear ribosomal genes and the trn L-F spacers of the chloroplast genome were used to resolve relationships in Iliamna Greene (Malvaceae). The eight species of Iliamna were included as well as representatives from Malacothamnus, and Phymosia. Iliamna, Malacothamnus, and Phymosia are thought to comprise the Malacothamnus Alliance based on chromosome numbers and morphological similarities. In the past, species of Iliamna and Phymosia were placed in the genus Sphaeralcea, and members of Malacothamnus were once included in the genus Malvastrum. Preliminary results in the present study indicate a strong affinity between Iliamna, Malacothamnus, and Phymosia. Sequences from the ITS region of Iliamna contained several insertion/deletion events preventing direct sequencing; whereas, in Malacothamnus and Phymosia, these events were not detected. This finding supports the hypothesis that Iliamna, with a base chromosome number of n=33, is a polyploid possibly derived from either Malacothamnus or Phymosia, in which n=17. The ITS region contained 12% parsimony informative sites, 120 of 678 basepairs sequenced, and the trn L-F spacers 1.3%, 13 of 1178 basepairs. A partition homogeneity test indicated the data sets to be incongruent. Topology of the phylogenies was examined and a few rearrangements of clades were found. It appears that Iliamna may not be monoplyletic, and that a few species may belong in another genus. Additional sampling from a wider variety of potential relatives is required before a clear picture of the evolutionary history of the genus can be developed.

Key words: Iliamna, ITS, Malvaceae, phylogeny, trn L-F