Inter-Sectional Hybrids in Peony

Ito hybrid is a distant cross between Paeonia suffruticosa and Paeonia lactiflora. In 1948, Ito of Japan successfully crossed with P. lactiflora'Kakoden'as female parent and Alice Harding, an intra-group hybrid of Paeonia suffruticosa. In 1974, Louis Smirnow, an American breeder, registered four new varieties of Ito from early hybridization: 'Yellow Crown', Yellow Dream,'Yellow Emperor'and'Yellow Heaven', which were named Itoh hybrids in memory of the first inter-group hybridization breeder in Japan.

The success of interspecific hybridization is an important innovative hybrid breeding achievement of Paeonia. It was first created by Toichi Itoh, a Japanese breeder, and then widely developed by American breeders. The first successful combination of interspecific hybridization came from peony group and P. lactiflora group. Although the two groups belong to the same family and genus, their growth habits are quite different. The peony group is deciduous shrub and the P. lactiflora group is herbaceous plant, and their flowering periods are usually staggered. Therefore, it was once thought that the hybrid of Herbaceous Peony and Paeonia lactiflora could not be realized.

The success of this interspecific hybrid combination has inspired many American breeders, who have published a number of new varieties, such as'Garden Treasure'and'Border Charm' in 1984 by Don Hollingsworth, and'Bartzella','First Arrival','Cora Louise'by Roger Anderson in 1986. The cultivation of these hybrids has greatly enriched the Itoh hybrid population. Their characteristics are unique: flower-shaped leaves resemble peony, but growth habits resemble peony, strong growth, long flowering period, second flowering, wind resistance and gray mildew resistance. Therefore, they are predicted to be the future of Paeonia plants. In short, the emergence of Itoh hybrids can be regarded as a milestone in inter-group breeding of Paeonia plants.

At present, yellow peony varieties are the most popular in the world, especially Itoh hybrids. Although they have not been widely planted yet, they are more and more popular because of their many excellent characteristics, such as resistance to pests and diseases, cold resistance, rich color, long flowering period and fragrance.

The application prospect of Ito hybrids in landscape gardening is very broad, and the commercial demand is very large. Some species with graceful tree-shaped and graceful leaf-shaped are suitable for garden planting or main landscape plants. For example, 'Bartzella', 'Garden Treasure' and 'Coppe rKettle'. Some short, compact and flowering varieties are suitable for flower mirror materials, such as ‘Border Charm’, ‘Viking Full Moon' and 'Lafayette Escadrille', and some long and straight pedicels are suitable for cut flower materials, such as 'Callies', 'Cora Louise' and 'Sequestered Sunshine'. In fact, all Itoh hybrids are the best landscape plants, which can be matched with Herbaceous Peony and Paeonia lactiflora with suitable flower color, flowering period and plant shape. They can be widely planted in special garden of Paeonia plants, herbal garden, rock garden, major parks, scenic spots, green space of residential areas, so that the florescence of the three groups can be extended to about 2 months. It can be imagined that the wide application of Itoh hybrids will greatly expand the application scope and prospects of peony and Paeonia peony populations.