The Genus Rosa comprises four sub-genera, the last of which, Eurosa, includes almost all of the roses ever cultivated. The Eurosa sub-genus contains ten sections. Roses have been classified botanically into these sections. Within some of the ten sections are further sub-divisions, particularly Indicae or Chinensis Section, and Gallicanae Section. These refined categories have largely occurred with the propagation of new hybrids and cultivars by man since the late 18th Century.

The following lists are presented by way of personal preference and as they appear in our catalogue. Verification of the correctness or otherwise of such classifications is proceeding still, using the relatively new method of chromosome counts to justify or correct anomalies.

Some categories such as Modern European Shrubs, and Modern Climbers comprise cultivars of more recent introduction, and because of the close integration of classes, are almost impossible to be classed with certainty in a particular Section or one of its sub-divisions. However they are included here in that Section most nearly appropriate.