APS Bulletin #321 March 2002

New First Generation Peony Crosses

Galen Burrell-Ridgefield, WA

Of the 70 or so species, subspecies and varieties of the Genus Paeonia only a limited number of these wild plants have contributed genes to the hybrid peonies we grow in our gardens. This is primarily because, in the past and even now, it is difficult to obtain true plants of the Genus Paeonia. There are two reasons why true peony species have been so difficult to obtain. One, is that many peony species grow in areas that until recently have been inaccessible to the West. Second, wild peonies that are sold by nurseries are often hybrids rather than true species because when in cultivation they cross-pollinate readily, if pollination is not controlled.

Professor A.P. Saunders was one of the few hybridizers who was able to obtain a limited number of true peony species. That's why most of the hybrids now available were produced by crosses made by Professor Saunders or came from plants he hybrided. (Please see The Best of 75 Years, published by APS, for some of the articles he has written about his crosses.)

Over the past 10-12 years I have accumulated, most from wild seed, nearly all species, subspecies and varieties of wild peonies. From these plants I try to produce true species seeds by crossing a plant of a particular species with a plant of the same species. I also cross-pollinate species to try and produce hybrids that look like the true species but are easier to grow than the true species (a good example is Paeonia parnassica). There is also a chance that hybrids produced in this manner could shed light on the evolution of some peony species.

The following is a list of some of the successful crosses that I have made and a description of the plants produced:

Paeonia steveniana (P. wittmanniana var nudicarpa)—I have not grown any crosses with P. steveniana to flowering but it does cross readily with many species. I have crossed it successfully with all subspecies and varieties of P. wittmanniana. I've also readily crossed it with P. parnassica. P. mlokosewitschii and P. mascula ssp. russoi.

Paeonia wittmanniana var. macrophylla—This variety also crosses readily with P. parnassica though I have not grown any of the progeny to flowering.

Paeonia cambessedesii —I have only attempted to cross P. cambessedesii with P. mlokosewitschii and P. mascula ssp. russoi. Both crosses produced many viable seeds but I have only grow these crossed with P. mlokosewitschii to flowering. All plants that have flowered look intermediate between mlokosewitschii and cambessedesii. They have pale yellow to ivory flowers with reddish-pink veining. All are pretty but are nearly as difficult to grow as cambessedesii.

I also have two plants which came to me as seeds of P. cambessedesii. Both are obviously hybrids — one looks nearly identical to cambessedesii but has white flowers, the other is more than twice as large as cambessedesii but it has leaves and flowers that are similar to cambessedesii. Both plants produce viable seeds and both plants are easier for me to grow than cambessedesii. This year I back-crossed both plants with cambessedesii and they both produced viable seeds.

Paeonia obovata — This is a pink form of obovata that I grew from seed collected on Mt. Fuji in Japan. This year I successfully crossed it with P. mairei.

Paeonia obovata var. willmotiae — I have only successfully crossed this variety with two species, mlokosewitschii and parnassica. This cross with mlokosewitschii only produced one seed and the subsequent plant only survived for two years. The cross with parnassica produced many seeds but none of the plants have yet flowered. These hybrids all look primarily like obovata but appear to be easier for me to grow than either parnassica or obovata.

Paeonia japonica — I made many crosses with this species but the only successful cross I made was with P.mlokosewitschii and that cross only produced one viable seed. After 3 years the plant, from that seed, looks intermediate between the two species. Hopefully it will flower this year.

Paeonia mascula ssp. russoi — I have three forms of russoi, one from Sicily, one from Sardinia and one from Corsica. All cross readily with one another. I have also successfully crossed these forms of russoi with P. mascula ssp. hellenica and P. mairei. though none of the plants produced has as yet flowered.

Paeonia potaninii var. trollioides — I have crossed this plant successfully with P. potaninii. P. lutea and P. potaninii "alba." This year I also crossed it with P. rockii ssp. linyanshanii.

Paeonia mascula ssp. arietina — I have only tried to cross this subspecies, P. parnassica. It crosses as readily with parnassica as it does with other plants of its own species. I have great hopes that these hybrids will have flowers like parnassica but will be as easy to grow as arietina, but so far none of them have flowered.

Paeonia emodi — I primarily only try to cross emodi with other plants of the same species since true emodi seeds are often hard to find. This year I have seedlings from emodi x parnassica. The seedlings look intermediate between the two species.

Paeonia brownii — Of all the crosses Anne Oveson and I have made with brownii the only (known) successful cross was made by Anne on a brownii flower with P. peregrina pollen. The seedlings were intermediate between brownii and peregrina but they only survived for one year.

Paeonia sinjinjangensis — For the past two years I have crossed this plant successfully with P. anomala.

Paeonia peregrina — Since peregrina has often been used for peony hybridization I have only attempted to cross it with one other species, parnassica. This cross has produced many seeds and will hopefully one day produce a plant that is as easy to grow as peregrina but with flowers like parnassica.

Paeonia parnassica—This is a very difficult plant for me to grow and the seed pods often dry up shortly after the plant has flowered. This year I obtained one seed with a cross with P. mascula ssp. arietina.

I have also crossed a few species with some of my hybrid peonies. So far I have only had one plant bloom and that was from a cross I made between "Anika," my own P. mlokosewitschii hybrid and P. mascula ssp. russoi.

I have been sending species peony pollen to Peter Waltz for some years. He has had a great deal of success using this pollen to fertilize hybrid and lactiflora peonies. There is a good chance that from his efforts one day we will have genes from many more species peonies represented in our garden hybrids.