Insights into the species delineation and population structure of Solidagoshortii (Asteraceae) through morphometric analysis.

Short's goldenrod, Solidago shortii (Asteraceae), is extant from a single l ocality in Blue Licks, Kentucky. Field studies demonstrated that this endem ic is a morphologically variable taxon, inspiring two questions. First, is the taxon known as S. shortii from Blue Licks the same species as originall y described by Torrey and Gray from an extirpated population at the Falls o f the Ohio River, Kentucky? Second, what is the extent of the morphological variation within and among populations of Short's goldenrod at Blue Licks? These questions were addressed through Principal Components Analysis (PCA) , Discriminant Function Analysis (DFA), and standard whole-plant herbarium specimen comparisons. Whole-plant comparisons with other members of Solidag o subsection Triplinervae revealed diagnostic characters suitable far the d elineation of S. shortii. All specimens of S. shortii from both the Blue Li cks and Falls of the Ohio localities shared diagnostic character states. Fo r morphometric purposes, specimens representing two sympatric goldenrod spe cies (S. ulmifolia and S. nemoralis) and one close phylogenetic relative (S . canadensis var, scabra) were sampled from the same locality as S. shortii . Vegetative and floral characters were analyzed for all four taxa. Specime ns of S. shortii from the Blue Licks vicinity formed a continuous cluster i n PCA with specimens from the Falls of the Ohio, a cluster which was distin ct from those formed by the other three species. In DFA, the Falls of the O hio specimens were imbedded in the cluster formed by the Blue Licks specime ns. Thus, the taxon at Blue Licks is indeed S. shortii, as established by m orphometric analysis and whole-plant comparisons. In terms of interspecific variation, S. shortii at Blue Licks exhibited a similar or greater range o f variation than either of the two more common Solidago taxa found at Blue Licks, S. canadensis var. scabra and S. memoralis. The range of morphologic al variation exhibited by S. ulmnifolia was slightly greater than that of S . shortii. These data also indicate a greater variability within and among Blue Licks populations of S. shortii than otherwise might be expected for a species of highly restricted distribution, and have major implications reg arding management policies.