TIMME, RUTH E.* and ISABELLE DE GEOFROY. Department of Biology, San Francicso State University, San Francisco, CA 94132. - A molecular phylogeny of the genus Polemonium (Polemoniaceae) using ITS sequence.
Polemonium consists of an estimated 28 species. Its distribution is
almost entirely Northern Hemisphere, with a single species also
occurring in Chile. The majority of recent phylogenetic studies of
this genus have focused on the seven alpine species, and have
neglected the remainder of the genus. Despite recent allegations that
the alpine members constitute a monophyletic group that may have
evolved from the subalpine P. pulcherrimum, ITS sequence data provide
a phylogeny where the alpine species are not monophyletic. It is
apparent that rather than undertaking further investigations of
relationships of subsets of Polemonium, it is more important at
present to explore the phylogeny of the entire genus. Results of this
study show several patterns: 1) Polemonium is a strongly supported
monophyletic genus; 2) the annual P. micranthum is sister to the rest
of the genus (all perennials); 3) the Mexican-southwestern P.
pauciflorum and P. mexicanum form a monophyletic group; 4) at least
two species, P. caeruleum and the western North American P.
pulcherrimum, are not monophyletic. Ultimately these results will
allow a determination of the actual number of lineages within
Key words: ITS, phylogenetic, Polemoniaceae, Polemonium