A stiff-branched, deciduous shrub, of rather gaunt habit when in the leafless state, but of luxuriant aspect when in full leaf, rarely more than 6 ft high in this country, but said to be twice that height in China. Branchlets thick, soft with abundant pith. Leaves doubly pinnate or doubly ternate, 9 to 18 in. long, the leaflets deeply divided into acute lobes or teeth, glabrous above, slightly hairy beneath. Flowers borne in May or June, up to 12 in. or even more across in garden varieties, but about half that width in wild plants; the latter have up to ten petals, and the colour is apparently either white with a maroon-purple blotch at the base of each petal, or in some shade of red, but in the garden varieties the petals are often very numerous, and the range of colouring wider. In the wild plants the flowers are fragrant, at least when they first expand, but this is not true of all the garden sorts, some of which have unpleasantly scented flowers. Stamens numerous, mostly converted into petals in the fully double garden varieties; anthers yellow. Carpels five, enclosed at first in a leathery outgrowth of the disk.
The moutan paeony, in its primitive state, is a native of northern China, in the provinces of Shensi, Kansu, and perhaps Szechwan, but has become rare in the wild (see further below). Its history, as a domesticated plant, goes back to the 7th century a.d., when the Tang dynasty had its capital at Changan, in what is now Shensi province. The first plants to be cultivated were brought into the imperial gardens from their native hills. As its popularity spread, it came to be raised from seed, and garden varieties arose, which at first were propagated by grafting on wild stocks, later on the roots of herbaceous paeonies. The first treatise on the moutan was written in the 11th century, by which time the centre of cultivation had shifted east to Loyang. In later centuries its culture spread southwards, and when Fortune visited China in the 1840s there were nurseries at Shanghai. But at Canton, whence came the early introductions to Europe, the winters are too warm to give the moutan the period of dormancy it needs. The thousands of plants that decorated the houses and gardens of the city early in the year were imported from the north and thrown away after flowering (Li, Gard. Fl. China (1959), Chap. 3; Fortune, Gard. Chron., Vol. 1 (1880), pp. 179-80). The name ‘moutan’ has a quite prosaic meaning – ‘male red’ – which probably dates back to a time when it was valued more for its roots than its flowers (W. Gardener, Gard. Chron., Vol. 160 (1966), p. 12). But it became known, from its sumptuous appearance and its association with the great days of the Tang dynasty, as the Hua Wang, the King of Flowers.
The moutan was introduced to Britain by Sir Joseph Banks, who ‘engaged Mr Duncan, a medical gentleman attached to the East India Company’s service, to procure a plant for the royal garden at Kew, where it was first received, through Mr Duncan’s exertions, in 1787’ (Loudon, Arb. et Frut. Brit., Vol. I, p. 252, but the date given by Aiton is 1789). The original plant remained at Kew until 1842, when, owing to building operations, it had to be removed. This importation – ‘Banksii’ (P. suffruticosa var. banksii G. Anders.) – is double, with a varying number of petals, purplish red at the base fading to almost white at the tips. The plant in Sir Joseph Banks’ garden at Isleworth was 6 or 8 ft high and between 8 and 10 ft wide in 1825. The type of the name P. moutan is probably the same as ‘Banksii’ (Botanical Magazine, t. 1154). The type of P. suffruticosa is not the Banksian introduction but a double, uniformly pink variety – ‘Rosea Plena’ – introduced in 1795. Of some historic and botanical interest is ‘Papaveracea’ (P. papaveracea Andr.), introduced in 1806, which was a more or less single white, very like Rock’s paeony discussed below. On the other hand, ‘Anneslei’, named in 1826 after the Earl of Mountnorris, seems to have been near to P. suffruticosa var. spontanea.
These early introductions came, via Canton, from somewhere in the moutan country of the north. The next set, sent by Fortune to the Horticultural Society during his first expedition to China in 1843-5, came from Shanghai, where the winters are cold enough for the moutan to thrive. Here there were several nurseries devoted to its culture, and the varieties grown were different from those sold by the Canton florists, being mostly darker in colour and more double. They were probably also newer and, one suspects, less vigorous. The Fortune introductions flowered in the Society’s garden and were given botanical epithets by Lindley, but seem to have died out. During his second expedition (1848-51) Fortune sent another set of thirty varieties from Shanghai to the firm of Standish and Noble, together with a supply of the herbaceous paeony used by the Chinese for grafting. In 1854 the plants were still growing in the containers in which Fortune had shipped them, but a special garden was planned for them, to be dug to a depth of 6 ft. Writing in 1880, the year of his death, Fortune lamented that the fine varieties he introduced had mostly been lost, but some seem to have found their way to the continent and been named, or renamed, there.
The moutan was carried to Japan by the Buddhists and became there, as in China, a favourite garden plant. Numerous varieties were introduced to Europe by Siebold in 1844 from the Imperial gardens at Yedo (Tokyo) and Miyako (Kyoto), all single or semi-double and grafted on moutan stock. Judging from the descriptions in his catalogue of 1856, some of these varieties must have been very fine, but they seem to have suffered the same fate as most of Fortune’s. Siebold also introduced the moutan stock used by the Japanese, which was of suckering habit and easily propagated by division. This he named ‘Germania’ and described the flowers as scented, ‘d’un cramoisi vif’. If he used this stock for his own propagations, the loss of his varieties is understandable, since it throws up so many suckers that the variety grafted on it is apt to be smothered. It was not until late in the century that Japanese varieties began to be imported in quantity. Today, the majority of the moutan paeonies in cultivation are of Japanese origin.
In the last century, many varieties were raised on the continent, and there were no doubt further importations from China. In the 1860s and 1870s some nurserymen listed a hundred or more sorts, very few of which have survived. So far as Britain is concerned, a study of the horticultural literature of the last century gives the impression that the moutan was never a common plant in gardens, and certainly does not confirm the notion that the Victorians were more successful with it than we are today. The choice of tree paeonies available in commerce in Britain now is not wide, but it includes what are acknowledged to be the best of the European varieties, such as the double pinks ‘Elizabeth’ (‘Reine Elisabeth’), ‘Comtesse de Tuder’, ‘Jeanned’Arc’ and ‘Louise Mouchelet’, and the famous white ‘Bijou de Chusan’, also double. The Japanese varieties, even when double, mostly have fewer petals than the Chinese and European sorts and a central boss of fertile stamens and pistils; the flowers are consequently less heavy and better poised. In the United States, one leading grower lists some 300 varieties. In Britain, the number regularly available is very limited and those imported from Japan are often not true to name, so to give a selection would be pointless.
In the wild, P. suffruticosa appears to be an uncommon plant, and little is known about it. The fact that its roots were valued by the Chinese as medicine, and the stems cut for firewood, may help to explain its present scarcity. At the end of the 17th century, according to a Chinese work, the moutan was so abundant on the Moutan-shan in Shensi that ‘the whole hill appears tinged with red, and the air round about for a distance of ten li is filled with fragrance’ (Bretschneider, Eur. Bot. Disc. China, Vol. I, p. 426). Yet when Purdom visited the mountain in 1912, he could find no trace of it. However, in 1910 he collected a specimen in Shensi, near Yennan, during his expedition for the Arnold Arboretum and Messrs Veitch (no. 338), from which Rehder described var. spontanea. In this the flowers were said to be rose-coloured, 4 to 5 in. wide, with ten petals. The foliage differs from that of most garden varieties in that the terminal leaflet is bluntly lobed and the lateral leaflets roundish in outline and more or less tridentate at the apex (Stern, op. cit., pp. 41-2). Purdom sent a few seeds, but all the plants raised were lost save one, which grew in Professor Sargent’s garden at Harvard. The Purdom introduction is said to be of suckering habit, and seems to be very like the moutan used at one time by the Japanese as stock for grafting the garden varieties. Purdom also found a wild moutan in S. Kansu, south of Minchow, where it is more abundant than in Shensi (Gard. Chron., Vol. 54 (1913), p. 230). He did not state the colour of the flowers he had seen, but apparently it was dark magenta crimson.
Despite the epithet spontanea, Purdom’s variety cannot be regarded as the sole or even the main ancestor of the garden varieties. A plant nearer to these, and of great beauty in itself, was found by Farrer in S. Kansu in 1914, during his journey with Purdom. This discovery grew near the border with Shensi about 40 miles north-east of Wutu (Kaichow). Farrer had seen ‘white blobs’ from afar and pushed through the thorn-scrub for a closer look. ‘Nor did I need near approach to discover what it was that I was hunting, for there, balancing rarely amid the brushwood, shone out at me the huge expanded goblets of Paeonia Moutan, refulgent as pure snow and fragrant as heavenly Roses. It grew tall and thin and stately, each plant with two or three thin, upstanding wands tipped by the swaying burden of a single upright bloom with heart of gold, each stainless petal flamed at the base with a clean and definite feathered blotch of maroon.’ (Gard. Chron., Vol. 56 (1914), p. 213; see also Farrer, On the Eaves of the World, Vol. I, pp. 110-13, 162.)
Farrer did not introduce his find, nor even collect a specimen. But eleven years later the American collector Dr Joseph Rock spent a year in the great Choni Lamasery in S.W. Kansu (Farrer, who had visited it with Purdom, spells its name ‘Jo-ni’). There he found a paeony very like Farrer’s, growing in the garden of the Yamen, which, according to the monks, had come from somewhere in Kansu (Journ. R.H.S., Vol. 64 (1939), pp. 550-2 and fig. 130). He sent seeds to the Arnold Arboretum, which were further distributed, but the date of this introduction is usually given as 1932, seven years after his stay at Choni. A young plant, received by Sir Frederick Stern in 1936 from Canada, flowered in his garden at Highdown, Worthing, in 1938 and by 1959 was 8 ft high and 12 ft across (Journ. R.H.S., Vol. 84 (1959), fig. 104). Rock’s tree paeony is so near to typical P. suffruticosa in its essential characters that a distinguishing botanical epithet is scarcely needed, but it could reasonably be placed under P. suffruticosa var. papaveracea (Andr.) L. H. Bailey, a name founded on the early introduction that Andrews named P. papaveracea (see above). Sir Frederick Stern pointed out that the only significant difference is in the colour of the sheath enclosing the carpels, which was described as purple in ‘Papaveracea’, whereas in the Rock introduction it is white. Rock’s tree paeony received a First Class Certificate in 1944.
Culture and Propagation. – In many parts of the country the tree paeony is very unsatisfactory. At Kew it grows too early in the spring, and the young growths and flowers are almost invariably destroyed by late frosts. It is this, not genuine winter cold, that is to be feared. In the colder and bleaker parts of the country, where it is not excited into growth so easily, the moutan grows to a size that it will rarely attain in low-lying districts near London. And no doubt some of the highly bred varieties now in commerce are more delicate than the old sorts first imported from China. The practice of grafting the garden varieties on the herbaceous paeony is responsible for many failures, but it is the customary method, and the best means of producing plants at a reasonable price. Provided it is planted so that the union between stock and scion is about three inches below the level of the soil, a tree paeony will in two or three years develop its own roots. It is then advisable to lift the plant and remove the herbaceous stock altogether, though this is not essential.
The tree paeony is seen to best advantage as an isolated specimen, and is less likely when grown thus to be attacked by the dreaded paeony blight than when crowded in by other shrubs. Warm, sheltered corners, where it may be excited into early growth, are not the best place for it. North-facing positions suit it well, and some shade is desirable, provided it does not come from overhanging branches. It will grow in any good garden soil, but thrives best on a calcareous or slightly acid loam. The ground should be deeply dug, and good drainage is essential. The tree paeony is a gross feeder and should be liberally mulched with leaf-mould or well-rotted manure (almost all experts counsel against the use of fresh manure). If an artificial fertiliser is used at planting time or as a top dressing, it should be one with a high proportion of phosphate and potash.
The worst enemy of the moutan is the paeony blight Botrytis paeoniae, a grey mould which causes the young shoots to wilt and die, and also kills the flower-buds. So virulent has this disease become in recent years that old plants have succumbed even in parts of the country where the moutan thrives best. Infected shoots, and all snags of dead wood, should be cut out as soon as noticed and burned. The disease can be controlled by spraying with captan, dichlorofluanid, thiram or zineb. Systemic fungicides such as benomyl and thiophanate methyl are also said to give a good control, but too frequent use of these fungicides might lead to the development of tolerant strains of the fungus. The threat of paeony blight is an additional reason for giving the plants an open, airy position, since the disease is fostered by damp, stagnant conditions.
The usual commercial method of propagating the moutan varieties is by grafting on the roots of an herbaceous paeony. As already remarked, this need not be a cause of failure if the plant is placed with the junction between scion and stock some three or four inches below soil-level. Most of the Japanese varieties set seed, which probably offers the best means of propagation for the private gardener (see further in the introductory note). Although the varieties will not breed true, a fair proportion of the seedlings will be worth keeping, provided the parent has well-formed flowers of a pure colour. A plant that is on its own roots, and has formed a stool, can be propagated by division during the winter; the rooted pieces should be potted-up and, when established, should be grown on in a cold frame until large enough to be moved into the garden. Layering is also a possibility, but owing to the brittleness of the branches of the tree paeony is not a very satisfactory method. Little is known about propagation by cuttings, since this method has never been used commercially to any extent, being too chancy. But some varieties can be increased in this way, using cuttings taken after flowering with a heel of the previous year’s wood (see Journ. R.H.S., Vol. 88 (1963), pp. 449-50). The young plants would have to be grown on in pots or a frame until strong enough to be planted in their final positions. For further details on propagation see the works by Haworth-Booth and Wister and Wolfe, cited in the introductory note.