Paeonia ostii in Britain

STEPHEN G. HAW

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Jn July 1992 a very important event occurred for anyone with a serious interest n tree peonies: Paeonia ostii was described For the first time. From the description, it was clear that this was a fine plant, distinct from other tree peonies. Its flowers were said to be large and white, with a pale reddish-purple flush, especially towards the base of the unblotched petals. The leaves were described as bipinnate, divided first into three and then again into as many as five leaflets per division, giving up to 15 leaflets in total. The specimens cited in the original description came from both cultivated and wild plants, with specimens from apparently wild plants collected in three Chinese provinces: Henan, Hunan and Shaanxi. More recently, it has become clear that Paeonia ostii is cultivated on a large scale in some areas of China, particularly near Tongling in Anhui province. It is grown princi­pally as a source of Chinese medicine. Recent searches for it as a wild plant have been largely fruitless. Only one population has been found, in western Henan. It is quite possible that it was formerly much more common in the wild but has suffered from over-collection of its roots for use as Chinese medicine.

For a time very little was known about this Peony outside China, but in the early 1990s, Dr. Gian Lupo Osti travelled to China with the specific aim of studying tree peonies. He brought back considerable information about Paeonia ostii, which was named after him by Professor Hong Tao and Zhang Jiaxun. In an article published in The New Plantsman in December 1994, he described seeing this Peony in cultivation in China. He also mentioned that a friend of his had imported plants of cultivars derived from this species (presumably to Italy) and that they had done very well in their first season.

Shortly after this, the first plants of Paeonia ostii were imported to the U.K. In the autumn of 1996, I was able to obtain a plant imported from a Peony nursery in Heze, Shandong province, China. It arrived bare-rooted and was planted immediately. My plant established well and produced flowers the following spring. It appeared to match the type description exactly, with up to 15 (often 13) lanceolate leaflets per leaf. Most leaflets were entire, though some­times terminal leaflets were more or less deeply bilobed or trilobed. Usually the lobes seemed to be the result of incomplete division of leaflets. If a leaf was divided into 15 leaflets, they were usually not lobed, but if it had only 9 leaflets, the terminal leaflets of its three main divisions were frequently deeply trilobed. As in most tree peonies, the leaves became smaller from the base of the shoot towards its tip, gradually diminishing to become bract-like and grading into the floral bracts.

After losing its leaves at the end of its first year in my garden, the plant very quickly came into growth again. This has been the case ever since. Buds often begin to expand in December, with new shoots attaining a few inches in length by February. The new growth is very suscepti­ble to frost damage and I regularly give the plant protection, wrapping it in horticultural fleece whenever frost seems likely to occur. Despite this, it is common for at least some leaves to suffer at least slight frost damage. This is potentially very harmful, as the damage can allow fungal diseases to attack the plant. This year, following a very mild winter, April was both cold and wet, with snow and slight frost (down to about -2°C) on a few occasions.

These conditions resulted in the worst fungal damage yet sustained by the plant.

In its first season, the Peony produced three shoots, each with a terminal flower. In its second season, it produced five shoots but only one flower. In the third season, eight shoots each produced a flower. This year (2000) only six flowers have developed fully, but at least three other buds were lost to frost or disease and 12 shoots have grown. The flowers had always begun to open in mid-April, but the very bad April weather this year delayed blooming until mid-May. The plant is now a good three feet tall and considerably larger than when I first received it. It produced its first basal sucker this year. The young growths of this Peony are greyish-green, strongly tinged with purple-red. The leaves do not become green until they are well developed.

After the first season of growth, the plant changed somewhat in appearance. It has been very interesting and instructive to observe this: clearly cultural conditions can significantly alter the external appearance of this tree peony (and presumably others also). The most obvi­ous change has been in the leaves. The leaflets have tended to become broader and generally larger and the leaves are rarely divided into as many leaflets as they were during the first season. Most leaves now have no more than 11 leaflets, even on strong shoots that produce large flowers. They are very similar in form to the leaves of many tree peony cultivars of the Paeonia suffruticosa group, the terminal leaflets normally being deeply trilobed. The flowers are also larger now than in the first season, up to eight inches across. So far, no viable seeds have been set from any of the flowers. This, I suspect, is because the plant is self-infertile, as seems often to be the case with tree peony species: I do not grow any other tree peony plants nearby. It has been reported that Paeonia ostii is capable of self-pollina­tion, but this may be because of confusion between the true species and very similar hybrid cultivars derived from it.

One of the most common cultivated tree peonies that is generally believed to derive

from this species is known as 'Feng Dan Bai' (sometimes translated "Phoenix White"). There is little doubt that this name is applied to a somewhat variable group of plants rather than to a single clone. It may sometimes be applied to the species itself. This makes it dif­ficult to be sure exactly how 'Feng Dan Bai' differs from the species, but it seems likely that most plants given this name have been grown from seed taken from Paeonia ostii, probably pollinated by a Paeonia suffruticosa cultivar. The same is very likely to apply also to pink-flowered plants called 'Feng Dan Fen' ("Phoenix Pink"). 'Feng Dan Bai' is cultivated on a large scale in the vicinity of Tongling in Anhui province, China. Its flowers are report­edly very fragrant (one possible difference from the species: the flowers of my plant of Paeonia ostii are not noticeably scented). It is reported to set plenty of viable seed. Both 'Feng Dan Bai' and 'Feng Dan Fen' are usually very fine plants and, like the species itself, very worthy of a place in the garden. Chinese nurs­eries now regularly export tree peonies abroad and these and other tree peonies are likely rapidly to become more readily available in the UK, Europe, the USA and elsewhere.

During the last few years, considerable work on tree peonies has been done by several Chinese botanists. More new species have been described and the nomenclature of known species revised. While the quality of work has varied and there has sometimes been some con­fusion about the status of some plants, most problems have now been resolved and a much clearer picture has emerged. Here I shall give a summary of the present situation according to the most recent publications by Chinese botanists.

There are now eight distinct species of tree peony recognized by Chinese botanists. Most are at least fairly well known in the West, but at least two are more or less unknown. They are Paeonia qiui, described only in 1995, and Paeonia decomposita. The former is a small plant, only about 60 cm or a little more in height, with usually biternate leaves with no more than 9 rather rounded and often lobed or toothed leaflets. The flowers vary from pale to deep pink and are about 10 cm in diameter. This is a very rare species known from only a few localities in the Shennongjia Mountains in western Hubei.

Paeonia decomposita, on the other hand, was described by Handel-Mazzetti as long ago as 1939, on the basis of a specimen collected by Harry Smith in western Sichuan in 1922. The single specimen has remained, little noticed, in a Swedish herbarium for decades. The name was included by Stern, in his great Peony monograph of 1946, in the synonymy of Paeonia suffruticosa. The late L.A. Lauener and I (in 1990) removed it from this syn­onymy as it clearly appeared distinct, but were only able to see a photograph of the type specimen and were unsure of its exact status. I surmised that it might be the same as a plant that had been described in China in 1958 under the name Paeonia szechuanica, but could not be sure of this without examining the type specimens of both these names. In correspondence with botanists in China I sug­gested that they might try to investigate this question and have been pleased to find that they have been able to do so. Paeonia decom­posita is now accepted as the correct, prior name of the species that has, since 1958, usually been referred to as Paeonia szechuanica. This is a very interesting plant, rather different from most other tree peonies, with leaves divided into as many as 63 leaflets and large, rose-pink flowers with smooth carpels that are only about half to two-thirds enveloped by the floral disc. It is restricted in the wild to very small areas in north-west Sichuan, where two distinct populations have recently (1997) been given subspecific status, the new subsp. rotundiloba differing from the type principally in having broader, more bluntly lobed leaflets.

Paeonia rockii, P. ostii and Paeonia suffruti­cosa are better known and I shall not comment further on them here, except to say that it is more or less certain that P. suffruticosa is of hybrid origin. One of its likely progenitors is the plant that was originally described as P. suffruticosa var. spontanea, based on specimens collected by Purdom in north China in the 1920s. This has now been raised to species rank and is usually called Paeonia jishanensis by Chinese botanists.

Finally, there are two species belonging to the Paeonia delavayi complex. Some appar­ently very thorough investigations into various populations of wild Peonies of this group has resulted in two important conclusions. The first is that most of the various taxa previously recognized cannot safely be distinguished. Paeonia lutea and P. potaninii and almost all their varieties have therefore been reduced to synonyms of Paeonia delavayi. This conclu­sion may be hard for many gardeners to accept, but it is supported by weighty evi­dence: in the wild in western China there are intermediates linking all the various plants that have often been given separate status. No firm characters can be identified allowing divi­sion into separate taxa. There is one notable exception to this, however. The plant usually known as Paeonia lutea var. ludlowii in the West has been raised to the rank of species, as P. ludlowii. This is based on the small number of carpels (and follicles) of P. ludlowii, which usually has only one carpel per flower, occa­sionally two, while P. delavayi has from two to four, five, six or even eight. As P. ludlowii is generally the more robust plant, with larger flowers, this is precisely the opposite of what might be expected if these were not distinct species. P. delavayi is also usually a widely-suckering plant, while P. ludlowii forms quite dense clumps of stems all arising close together. The floral difference, in particular, seems a good reason for these to be considered two separate species.

The last decade has therefore seen a great deal of work done on tree peonies and the recognition of several new species, some previ­ously unknown. With the recent founding of the British Peony Society and improved con­tacts with growers in China it is to be hoped and expected that the cultivation of tree peonies in Britain will go from strength to strength.

REFERENCES

HAW, S.G. & LAUENER, L.A. (1990). A review of the infraspecific taxa of Paeonia suffruticosa Andrews. Edinburgh Journal of Botany, 47(3): 273-281.

HONG, D.-Y. (1997). Paeonia (Paeoniaceae) in Xizang (Tibet). Novon, 7(2): 15661.

HONG, D.-Y. (1997a). Notes on Paeonia decomposita Hand.-Mazz. Kew Bulletin, 52(4): 957-963.

HONG, D.-Y. & PAN, K.-Y. (1999). Taxonomical history and revision of Paeonia sect. Moutan (Paeoniaceae) [in Chinese with English abstract]; Zhiwu Fenlei Xuebao/Acta Phytotaxonomica Sinica, 37(4): 351-368.

HONG, D.-Y. & PAN, K.-Y. (1999a). A revi­sion of the Paeonia suffruticosa complex (Paeoniaceae); Nordic Journal of Botany, 19(3): 289-299.

HONG, D.-Y., PAN, K.-Y. & PEI, Y.-L. (1996). The identity of Paeonia decomposita Hand.-Mazz. Taxon, 45(1): 67-70.

HONG, D.-Y., PAN, K.-Y. & YU, H. (1998). Taxonomy of the Paeonia delavayi complex

(Paeoniaceae); Annals of the Missouri Botanic Garden, 85(4): 554-564.

HONG, T. & OSTI, G.L. (1994). Study on the Chinese w'rid woody Peonies (II): new taxa oi Paeonia L. Sect. Moutan DC. Bulletin of Botanical Research (Harbin), 14(3): 237-240.

HONG, T. et al. (1992). Study on the Chinese wild woody Peonies (I): new taxa of Paeonia L. Sect. Moutan DC. [in Chinese and Latin with English abstract]. Bulletin of Botanical Research (Harbin), 12(3): 223-234.

OSTI, G.L. (1994). Tree peonies revisited. The New Plantsman, 1(4): 195-205, 247.

PAGE, MARTIN (2000). A cultural revolution. The Garden, 125(5): 336-339.

PEI, Y.-L. & HONG, D.-Y. (1995). Paeonia qiui - a new woody species of Paeonia from Hubei, China. Zhiwu Fenlei XuebaoMcftf Phytotaxonomica Sinica, 33(1): 91-93.

STERN, F. C. (1946). A Study of the Genus Paeonia. London: RHS.

ZOU, Y.-P., CAI, M.-L. & WANG, Z.-P. (1999). Systematic studies on Paeonia sect. Moutan DC. based on RAPD analysis [in Chinese with English abstract]. Zhiwu Fenlei Xuebao/Acta Phytotaxonomica Sinica, 37(3): 220-227.

Stephen G. Haw, Worton Edge, Over Worton, Chipping Norton, Oxon. OX7 7EW. UK

Letter (from Will McLewin)

Paeonia ostii

I would like to express a rather different view of Paeonia ostii to that presented by Stephen Haw in his article Poeonia ostii in Britain (New Plantsman 7(3): 165-169 (2000). I am not at all convinced that Paeonia ostii is actually in Britain but I am convinced that the plant he discussed is not a true species but simply an exam­ple of a group of peonies culti­vated in China on a vast scale.

When Paeonia ostii was first described in 1992 my reaction was sceptical and the plant described was certainly not "dis­tinct from other tree peonies". All tree peonies in China are utilised to provide 'Dan Pi' - the root bark used for medicinal pur­poses. The 'Feng Dan' peonies have the largest, most rapidly developing roots and provide the highest yield of this substance and consequently are very extensively cultivated and have been for centuries. It is important to under­stand that 'cultivation' in this context covers not only organised agriculture but ad hoc collecting and planting in 'the wild'.

The last two decades has seen a lot of interest, research and field work in China on woody peonies but there is a strong element of competition and publications are contradictory. Once it was realised that there was no recog­nised ancestral species for 'Feng Dan' peonies, identifying and find­ing such a plant became an impor­tant goal for Chinese botanists. Miraculously, as soon as a few 'species plants' were found and the 'new species' described they were very soon widely available commercially. That this species, also known as the Yangshan peony, should have been named after Gian Lupo Osti is bizarre unless largesse and a subtle Chinese sense of humour are involved. Incidentally, when I talked with Gian Lupo Osti about P. ostii in 1996 he said that when he was in China he never saw true wild species plants.

My view at present is based on discussions with several Chinese botanists, who work on 'Chinese Tree Peony', Wang Lianying et al., the most authoritative book on the subject, and also my experi­ence with hundreds of plants from China labelled P. ostii, some with wild provenance and not all from a (commercial?) "Peony nursery in Heze". I think that the overall situation is very complex, far from resolved and that while simple descriptions and state­ments are comforting they are actually misleading and create more problems in the long run. I am unhappy with pronunciations about species plants based on one or two herbarium specimens and one or two actual plants that do not have impeccable wild provenance, especially so where the context is a vast country like China and where the plants involved have been extensively cultivated for centuries. Feng Dan peonies are a distinct group. Distinct that is from other groups - suffruticosa, rockii and delavayi -but plants with intermediate morphology are common and each of these groups (I use the word group informally) remains a 'can of worms'. In time some sort of resolution may emerge but not without the benefits of a lot more field work and of molecular analysis.

There are many statements in Stephen Haw's article which seem to me to be 'unfortunate'. Three in particular to which I draw attention are:

(i) He says the plant on which his comments are based "appeared to match the type description exactly" but after the first season of growth, the plant changed somewhat in appearance". Presumably it now does not match the type description exactly and consequently is no longer P. ostii!

(ii) He says that the name Feng Dan Bai is applied to a vari­able group of plants not a sin­gle clone. Lest anyone is seriously misled by this state­ment it should be emphasised that in Chinese horticulture varietal names are applied on the basis of 'appropriate' morphology and the concept of a clonal name (i.e. strict vegetative propagation only) is not adhered to. Giving vari­ety names to plants grown from seed that have the right appearance is standard prac­tice. The same practice is common alas in British horti­culture, the difference is that in China there is no pretence otherwise "you want a Ming vase? - We'll make you one".

(iii) He says that "it seems likely that most plants of Feng Dan Bai have been grown from seed taken from Paeonia ostii, probably pollinated by a P. suffruticosa cultivar". It seems far more likely to me, and actu­ally credible, that they are grown from seeds collected from plants of Feng Dan Bai.

Will McLewin