DROUIN, JOSéE NADIA* AND LUC BROUILLET. Institut de recherche en biologie végétale, Université de Montréal, 4101 Sherbrooke est, Montréal, Québec, H1X 2B2. - Dandelions (Taraxacum, Asteraceae) of the Gulf St-Lawrence: how many species are there?
Although dandelions are easily recognized by everyone, their taxonomy
remains still obscure. The phylogenetic study of this group is
difficult since the majority of species are polyploid and asexually.
Section Ceratophora in the Gulf St-Lawrence area (Eastern North
America) reflects this difficulty. According to different authors, 3
to 11 apomictic species may be present in the area and several of them
could be endemic. The relationships among these species and with
their relatives have been investigated morphologically but the results
are not conclusive. The object of the present study is to establish
the status of supposedly endemic species and to clarify relationships
among them and with their relatives. A preliminary molecular
systematic study based on the amplification, cloning and sequencing of
the 5S rRNA spacer regions has proved to be relevant. The spacer
length is approximately 370 bp. Many characters are useful and
preliminary results appear to support some of the hypotheses of
traditional relationships. The percentage of divergence varies from 2
to 17 between species. Confrontation of this analysis to the
morphological study may help determine relationships within this
complex group and thus appreciate the diversity of the taxon in the
Gulf St-Lawrence area.
Key words: 5S-rRNA, Dandelions, Gulf St-Lawrence, Phylogeny, Taraxacum