The Dwarf Flowered Heartleaf (DFH) is afforded protection under the Endangered Species Act and is listed as a “Threatened” species by the United States Fish and Wildlife Service. The species is distributed across a range that extends from the western Piedmont of North Carolina to the northwestern Piedmont of South Carolina. There are approximately 190 known sites where this plant occurs in this region. Due to current U.S. Fish and Wildlife Service guidelines regarding the treatment of Federally Threatened plants, threats to populations of this species must be considered in any projects that involve federal funds. This is particularly problematic issue to address for this species, since it is distributed in one of the fastest growing areas of North Carolina.
In the development and construction of highway projects in North Carolina, there is a need to be able to locate populations of the DFH and provide conservation measures to offset impacts to the species. This means being able to 1) differentiate this species from co-occurring related species, and 2) differentiate this species from hybrid individuals. Although flower size and pollen surface features have been shown to be effective characters to identify DFH to species, no characters have been shown to be effective for species recognition when the plant is in a vegetative stage. This essentially shortens the period of field identification to, at best, six weeks.
The DFH distribution overlaps with five species across all of the DFH range and two species at the western periphery of the DFH range. Several botanists have described individuals in the field that appear to be intermediate between the DFH and one or more of these co-occurring species. Based upon conversations with NC Department Of Transportation botanists, it appears that individuals with intermediate morphologies have made it difficult to identify some of populations to species, using information provided in peer-reviewed dichotomous keys (Gaddy 1987, FNA 2003), even with access to flowering materials.
The project will extensively sample across the range of the DFH and less extensively from the five co-occurring species (H. arifolia var. ruthii, H. minor, H. heterophylla, H. virginica, and H. shuttleworthii) and the two species at the western periphery of the range (H. rhombiformis and H. contracta). Photographs and scanning electron micrographs of flower and leaf will be obtained. A microsatellite library will be generated, and then used to screen for polymorphisms across the range of the DFH. We will then use the developed library to genotype individuals across the range of the DFH, as well as the putative hybrids and hybridizing taxa. Maps will be generated to examine the morphological, anatomical and molecular variation within and between species across the landscape. These data will then be used to develop a robust set of characteristics that can be used to identify the DFH and to differentiate members of the target species from congeners and hybrids.
North Carolina DOT will use the information obtained from this study to be more efficient in planning for long-term highway corridors and to effectively identify mitigation sites in the region. Developed molecular markers can be used to identify DFH populations throughout the year instead of only during the flowering season. All of the generated data will enable NC DOT to be responsive to US Fish and Wildlife in their reassessment of the status of the DFH.
