This study assessed S. hostii as a tetraploid (2n = 68) species and further evidence was provided when its hybrid with S. aucuparia (2n = 34) was proved to be triploid (2n = 51).
Úlfareynir (S. hostii) reyndist vera fjórlitna tegund (2n = 68) og blendingur hans við ilmreyni þrílitna (2n = 51).