PANERO, JOSE L.1*, BRUCE G. BALDWIN2, EDWARD E. SCHILLING3, and JENNIFER A. CLEVINGER4. 1Section of Integrative Biology, University of Texas, Austin, TX 78712; 2Jepson Herbarium & Dept. of Integrative Biology, 1001 Valley Life Sciences Bldg. #2465, University of California, Berkeley, CA 94720-2465; 3Department of Botany, University of Tennessee, Knoxville, TN 37996-1100; 4Department of Biology, James Madison University, MSC 7801, Harrisonburg, VA 22807. - Molecular phylogenetic studies of members of tribes Helenieae, Heliantheae, and Eupatorieae (Asteraceae). 3. General systematics and proposed taxonomic changes in current classification.
Most genera of the HHE clade are grouped in two major sister clades.
One of the two clades contains the core Heliantheae genera and in turn
has two major clades. Each of the two core Heliantheae clades has as
its basalmost lineage a white ligulate genus. The monotypic genus
Rojasianthe and Montanoa share white ligules, acrescent pales after
anthesis, and a chromosome number of x = 19. Rojasianthe is basal to
the lineage containing the Verbesininae s. str., the Engelmanniinae
sister to the Rudbeckiinae, and this sister to a terminal clade
containing selected members of the Ambrosiinae, Helianthinae,
Zaluzaniinae, Zinniinae, the conical receptacle genera of the
Ecliptinae (exemplified by the genus Acmella), and the epaleate genus
Trichocoryne. The genus Parthenium is sister to Dugesia; both genera
share a similar achene dispersal mechanism and floral sexuality
pattern. The genus Ambrosia in some of the trees is sister to Encelia
and basal to most genera of this clade. Encelia is not the immediate
sister taxon of the Helianthinae. The other clade of core Heliantheae
has the genus Montanoa as its basalmost lineage sister to the core
Ecliptinae. The major clade sister to core Heliantheae contains a
disparate group of taxa ranging from traditionally helianthoid paleate
taxa such as those classified under subtribes Galinsoginae,
Melampodiinae, Milleriinae, and Guardiolinae, along with epaleate taxa
such as Galeana/Villanova, the Peritylinae, and the Madiinae. Support
for deeper clades of the major group of paleate and epaleate taxa that
includes Eupatorieae is weak, but the component taxa are probably
closely related based on strong support for other deep clades of the
HHE tree. The results outlined here provide support for changes in the
classification of tribes Helenieae and Heliantheae. A tentative
classification scheme for the HHE clade will be presented.
Key words: Asteraceae. Helenieae, chloroplast DNA, Eupatorieae, Heliantheae, phylogenetics