Using statistical analysis of morphological characters , Ungricht et al. in 1998 found no distinct clusters among the specimens they examined .
Using statistical analysis of morphological characters , Ungricht et al. in 1998 concluded that Linnaeus 's M. officinarum is a single , variable species .
Using statistical analysis of morphological characters , Ungricht et al. in 1998 found no distinct clusters among the specimens they examined and concluded that Linnaeus 's M. officinarum is a single , variable species .