Earlier ITS analyses have shown that North American asters are polyphyletic and unrelated to Eurasian ones. To confirm this result, we used data of chloroplasic origin. We sequenced the trnL-trnF spacer as well as the trnL intron for 56 Astereae taxa. The chloroplastic data have less informative characters than the ITS data. The trees generated from cpDNA have less resolution than ITS ones. The number of significant indels in the aligned sequences are 6 for cpDNA and 20 for ITS. In the cpDNA tree, Eurasian asters are distinct from the North American clade. The cpDNA data do not conflict with the ITS ones and we combined the two sets (45 taxa). The combined analysis resulted in a tree with a topology similar to the ITS data but with increased support for several branches. This confirms that North American asters are distinct from Eurasian ones. One cpDNA indel present in these asters is lacking in the North American clade, but the polarity of this character cannot be assessed due to lack of data in Astereae. Dollingeria-Eucephalus are basal, and two major lineages are observed with our taxon sampling: Chrysopsidinae-Solidaginiae clade (low support), and Symphyotrichinae-Machaerantherinae clade. Within the latter, the eurybioid asters do not appear to form a monophyletic entity. In the Symphyotrichinae, Canadanthus, then Ampelaster are basal to a Psilactis- Symphyotrichum polytomy. Although the cpDNA data have little resolution, they added support to the ITS tree in the combined analysis. Indels proved to be useful markers. Although cpDNA data are not variable enough within genera of Astereae, they may prove useful to assess intergeneric relationships within the tribe. More cpDNA regions need to be sequenced, however, to achieve a resolution similar to that obtained with the ITS data set.

Key words: Astereae, asters, cpDNA, ITS, Molecular phylogeny, North America