Abstract:
Considerable disagreements about the classification system of
Trapa L. still exist, with no current unified view. The Amur River and Tumen River basin is an important species distribution and diversity center of
Trapa. To reveal the geographical distribution pattern and morphological diversity of
Trapa plants in this basin, we conducted field surveys and research. We found 11 species and 8 types of intraspecific variability from 28 lakes in the area, indicating that
Trapa exhibited rich morphological diversity. In addition, 354
Trapa specimens were also consulted and a total of 92 distribution data locations were obtained. The geographical distribution pattern of the 11 species was not balanced. The distribution of
Trapa maximowiczii Korsch.was the widest, while
Trapa incisa Siebold et Zucc.,
Trapa khankensis Pshennikova, and
Trapa kozhevnikovirum Pshennikova showed narrow domain distribution. The Eastern Ussuri River and Tumen River basin was found to be the diversity distribution center of
Trapa, and might be a Quaternary glacial refuge. Interspecific morphological features of
Trapa were relatively stable.
Trapa manshurica Fler.,
Trapa potaninii V.Vassil.,
Trapa japonica Fler.,
Trapa sibirica Fler., and
Trapa maximowiczii Korsch.exhibited eight intraspecific variabilities. Most morphological characters were stable within the population, whereas variabilities were obvious between populations. The diffusion limit of gene flow was an important factor resulting in the imbalanced distribution patterns and intraspecific variability of
Trapa. This research lays the foundation for clarifying
Trapa classification. Based on the results, combined with molecular marker technology, studying the phylogenetic relationships could have significant impact in revealing the evolutionary history of the
Trapa genus.