Systematics Section / ASPT
Klotz, Larry , Loeffler, Carol .
Morphological Analysis of Shooting Star Populations (Dodecatheon, Primulaceae) in Pennsylvania.
Two species of Dodecatheon (D. meadia and D. amethystinum) are reported from Pennsylvania, but the populations overlap in the characters that previous authors considered to distinguish these species. We marked 60 randomly selected plants in each of 14 populations: six in the Potomac drainage and eight in the Susquehanna drainage. The Potomac populations occur in upland woods whereas the Susquehanna populations occur on rock outcrops in woods or wooded streambanks. We assessed 20 characters in the same plants in flower and fruit. The populations differ, often significantly, in the means of all characters; but they overlap in the ranges. For example, corolla color varies from dark pink to pale pink (rarely white) in all populations. Previous authors considered capsule wall thickness to be the most reliable distinction between the two species. In Pennsylvania, capsule wall thickness shows the most consistent difference of any character between the two geographic groups. The means and ranges of capsule wall thickness in the Susquehanna populations resemble the values reported by previous authors for D. amethystinum. In five of the six Potomac populations, mean capsule wall thickness resembles D. meadia, but all of the ranges overlap with the values reported for D. amethystinum. All of the Potomac populations differ significantly from all of the Susquehanna populations in mean capsule wall thickness. However, all 14 populations show some degree of range overlap. Because of the range overlap in this and the other characters, we conclude that the Pennsylvania populations of Dodecatheon represent a single taxonomic species. On the basis of capsule wall thickness, the Susquehanna populations are referable to D. amethystinum whereas the Potomac populations are transitional to D. meadia.
1 - Shippensburg University, Biology, 1871 Old Main Drive, Shippensburg, Pennsylvania, 17257, USA
2 - Dickinson College, Biology, P. O. Box 1773, Carlisle, Pennsylvania, 17013-2896, USA
Presentation Type: Poster
Location: Special Event Center (Cliff Lodge)
Date: Tuesday, August 3rd, 2004
Time: 12:30 PM