What are "Intersectional" or "Itoh" peonies?
They are a cross between a herbaceous peony and a tree peony and combine some good features of both. Typical of tree peonies, they have bright and/or blended colours e.g. strong yellow. They also tend to have narrow-leaved foliage like tree peonies and make very good compact landscape bushes. However, they also have the growth habits of the herbaceous peonies by sprouting up vigorously every spring and more or less dying back in the autumn. They are cut back to the ground in an autumn clean-up.
Overall they usually exhibit great vigour and health, and make excellent landscaping plants, but tend to have more open flowers and are not often used for cutting.
The name "Itoh" comes from the Japanese nurseryman who first achieved this type of cross, and the name "Intersectional" comes from the fact that they are crosses between two different sections of the peony family.