Winter Rose is the common name for Hellebores.
More specifically the name Winter Rose or Lenten Rose refers to Helleborus x hybridus, previously known as Helleborus orientalis or orientalis hybrids.
The other common name applied to Hellebores is Christmas Rose which refers to Helleborus niger.
Hellebores are in the Ranunculus family and are therefore related to Clematis, Aquilegias and Delphiniums. Despite their common name Hellebores are not closely related to the genus Rosa.