Finding Characters that will Differentiate Six Very Similar Packera (Ragwort) Taxa in the Upper Midwest

The North American plant genus Packera is a member of the Asteraceae (Sunflower Family). Most of the approximately 70 Packera species are morphologically distinct and occur in different geographic areas or microhabitats. However populations of the widespread, P. paupercula complex are variable in morphology, chromosome number, and ecological requirements. One undescribed group of tetraploid populations currently recognized in P. paupercula occurs in the Upper Midwest and Canada, including northern Minnesota. These “Northern Tetraploids” may merit recognition at the species or varietal level. Northern Tetraploids are very similar in morphology to other diploid members of the P. paupercula complex in our region (varieties paupercula, savannarum, and pseudomentosa) and to P. plattensis a tetraploid prairie species found in western Minnesota. As part of a larger study that seeks to describe and classify the Northern Tetraploids, I measured 13 characters on 82 herbarium specimens that include these six Packera taxa. I used one way Analysis of Variance (ANOVA) to determine which characters best differentiate the taxa. While no one character will differentiate among all taxa, mean flowering date, involucre length, ray length, and ratios derived from basal leaf measurements were significantly different in some pairwise comparisons. Used in combination, these characters will provide useful information for biologists attempting to identify these taxa in the field. Furthermore, naming a new species or variety requires valid publication that includes a thorough morphological description and a key to related species