BECK, JAMES B.1*, GUY L. NESOM2, PATRICK J. CALIE3, GARY I. BAIRD4, RANDY L. SMALL5, and EDWARD E. SCHILLING5. 1Department of Biology, Washington University, St. Louis, Missouri 63130 USA; 2Botanical Research Institute of Texas, Fort Worth, Texas 76102-4060 USA; 3Department of Biological Sciences, Eastern Kentucky University, Richmond, Kentucky 40475 USA; 4Department of Botany and Range Science, Brigham Young University, Provo, Utah 84602-5181 USA; 5Department of Botany, University of Tennessee, Knoxville, Tennessee 37996-1100 USA. - Overview of Subtribe Solidagininae (Asteraceae: Astereae).
Subtribe Solidagininae O. Hoffm. is a generally accepted name
referring to a portion of the tribe Astereae, but concepts of its
morphological circumscription and constituent genera have varied
widely. Sequences from the internal transcribed spacer (ITS) of
nuclear rDNA were examined in an attempt to define Solidagininae and
to test hypotheses regarding major lineages within this group.
Parsimony analyses indicate that a monophyletic group can be
identified that largely corresponds with Solidagininae as previously
delimited by Nesom (1994)-characterized by glandular-punctate leaves,
a corymboid capitulescence, yellow rays, disc style branches with
papillate collecting appendages, and terete, multinerved achenes with
a 1-seriate pappus, although exceptions abound. The group itself is
less strongly supported than each of three constituent lineages. A
"Gutierrezia lineage" composed of genera producing
small, turbinate achenes and basally indurate phyllaries occupies the
basal position within the subtribe. An "Ericameria
lineage"-an anomalous cluster of perennial shrubs
(Ericameria) and annual herbs (Pentachaeta,
Rigiopappus, Tracyina) is explicitly placed in the
subtribe for the first time. The largest of the subgroups is the
"Solidago lineage"-composed of a primarily herbaceous
group (Solidago and close relatives) and a primarily woody one
(Chrysothamnus and close relatives). The Solidago
lineage exhibits low levels of sequence divergence within and between
member genera, indicating a recent radiation, and the data are
insufficient to draw conclusions regarding its internal phylogenetic
structure. Solidagininae is almost an entirely North American group
and apparently arose from near the very base of the "North
American clade" of Astereae, although several of the genera have
secondary radiations in South America.
Key words: Astereae, ITS, Solidagininae, Solidago