Kent Alpine Gardener's Diary
This entry: 17 October 2014 by Tim Ingram
The species of Paeonia - Christine Skelmersdale
Peonies - talk to the East Kent Group of the AGS, 10th October 2014
At the end of her talk to us Christine Skelmersdale said that peonies were just her hobby. Well I can say in all fairness, 'some hobby!'. We were given such a comprehensive talk on the species of Paeonia, with slides from very many of her friends and colleagues who have travelled the world, and showing the variation and often botanical difficulties in assigning names to plants, that even those in the audience who know them quite well learnt a great deal more.
Christine has grown peonies, like so many gardeners, ever since being introduced to them in childhood. They are long-lived plants that given suitable conditions only improve with age, and the flowers, if individually quite fleeting, can be astonishingly beautiful and profuse on mature plants. Jim Archibald grew one of the finest of all collections of herbaceous species in his stock tunnel in south Wales, and distributed seed from plants of known wild provenance. They are universally admired, especially in China (and Japan) where tree peonies have been grown and selected for millenia, and used medicinally. A plant of the famed P. rockii in a garden is always the sign of the true plants-person, especially now that seed is much more readily available and it is easier to raise plants yourself.
Taxonomically they fall quite simply into three groups, if from thereon more complexities arise: the tree peonies (MOUTAN), the two N. American species, P. brownii and P. californica (ONEAPIA), and by far the biggest and most widespread section, the herbaceous species (PAEON). The two American species most closely resemble the tree peonies of China, though smaller and herbaceous, a feature brought out well in the photographs Christine showed. As far as gardeners are concerned they have little ornamental appeal (and are difficult to grow!), even if having considerable botanical interest.
Probably amongst the easiest of all in the garden are the smaller flowered tree peonies, known variously under the names P. delaveyi, P.potananii, P. lutea, and P. ludlowii. There can be great variation in colour and form in wild populations even in the same localities, which Christine showed us convincingly, and so they can be regarded as all variants of the single species P. delaveyi, or subdivided according to geographical separation. Horticulturally more names are useful for gardeners, but scientifically fewer are likely to be more accurate. This same conundrum is even more true of peony species showing wide distributions in other continental regions, where hybridisation is likely and what appear as distinct forms (including in colour) may not be genetically very different. The more you know, in some ways, the less becomes clear (but as Christine said it is the variation and detail of these plants that does appeal so much to keen gardeners).
Practically it is the places that specific plants come from that are most important in determining their adaptability to different gardens. Some of the most beautiful (and that is saying a lot!) are those species limited to the Mediterranean islands: P. clusii from Crete, P. rhodia from Rhodes, and P. cambessedesii from Majorca. In fact the last named can make a wonderful plant in mild gardens such as the Chelsea Physic, whereas the first two are rarely seen and grown successfully. The very widespread and variable P. mascula from similar Mediterranean regions is equally good and often more cold tolerant.
Delineating species ecologically as well as morphologically has logic, and the various yellow species from the Caucasus and further south occur sometimes in woodland and sometimes in open hot and dry sites. The recent description of P. wendelboi (Journal of the Alpine Garden Society, Vol. 82, p. 230, 2014) shows how more detailed and local investigations of plants is bound to result in a more sophisticated understanding of them, and this is in part driven by horticultural attraction as well as scientific exactitude.
Christine pointed out that the species from more extreme continental climates, experiencing very cold winters and hot dry summers, often benefit from light shade in British gardens, where woody plants will keep the soil drier in summer. The exquisite and very distinct P. tenuifolia does grow well in our fertile loam in the open garden, but much better in the hot summer climate of the Czech Republic, as I have shown previously. (And the Botanical Garden at Prague has a particularly fine collection of species). Perhaps it is no surprise that a gardener and nursery-lady so adept at growing bulbs should also be attuned to species of peony that grow in seasonally very varying climates.
If, in general, the species peonies are less commonly grown and trickier in the garden than the many hybrids, they are also amongst the most beautiful of all plants in flower and stimulate experiment and discovery of suitable growing conditions. It is rare to hear from someone who does know and grow them so well, and to see such a fine range of photographs of them in nature, and a great encouragement for others of us to try and grow more species too.