| Abstrakt: |
Morus rubra, commonly known as red mulberry, is rare in many areas of its native range in the United States. Previous studies have conflicting reports about the occurrence of M. rubra at its northwestern boundary. The main objectives of this study were to determine the northwestern boundary of the native M. rubra and provide diagnostic features through analysis of herbarium records, field observation and molecular data. We studied herbarium specimens housed in the major regional herbaria, conducted field studies in Iowa, Kansas, Minnesota, South Dakota and Wisconsin, and analyzed nuclear and chloroplast DNA sequences. We found no occurrence of M. rubra in Minnesota and South Dakota. We also did not find M. rubra trees in some counties of Nebraska and Iowa as reported earlier. Herbarium records augmented by the nuclear ITS and chloroplast trnL-trnF DNA sequences indicated that previous reports were perhaps the results of misidentification that stemmed from introgressive hybridization of M. rubra with morphologically similar, but phylogentically, non-sister M. alba. In the majority of cases, M. rubra identification was mistaken for exotic invasive M. alba or hybrid individuals. The results from this study have clarified the geographical range of M. rubra near its northwestern boundary and provided salient features for identification of the two species. This information would have implications in developing conservation/management plans for the rare red mulberry in the Midwest United States. [ABSTRACT FROM AUTHOR] |
