INTRODUCTION

'"The late Mr. H. J. Elwes of Colesbourne suggested to me many years ago that a new study the of the genus Paeonia should be undertaken. The names of paeony species were in much confusion as there was a set of traditional names in gardens and another in systematic literature ; further, since the last study of the genus, published by Huth in 1891, several new species have been discovered and described. This genus is so interesting and also so useful for the garden that it seemed worth while to try and get the nomenclature in order; this has necessitated an examination of the whole genus. I began to collect the different species in 1919 and grew them in my garden at Highdown, Goring-by-Sea, Sussex. The plants were either collected from the natural habitat of the species or raised from seed collected from the wild plants, for it was essential that the plants examined should be examples of the actual wild species from their particular districts.

I have based the revision of the genus entirely on specimens collected in a wild state and have studied the herbaria of the Royal Botanic Gardens, Kew, the Royal Botanic Garden, Edinburgh, the British Museum, Musee nationale d'Histoire naturelle, Paris, and the Manchester Museum. The authorities of the herbaria of Calcutta, Leningrad and Vienna have also been kind enough to lend some of their specimens for examination. I am grateful to the officials of all these herbaria for their assistance.

Each species has been described from dried specimens collected in the natural habitat of the wild plant; there are a few exceptions where no wild specimens exist in well-known herbaria and where it is not known whether such paeonies which have been described as species are species or forms that have arisen in gardens. Descriptions have not been given of known garden forms or hybrids, although reference has been made to some of the best known garden forms.

One of the main difficulties of the study was to straighten out the confusion among the names of the different species, especially among the European species. I found it necessary to go through the whole of the literature of the genus in order to obtain the required information as to how each name has arisen and to which species the different names really belong. In going through this literature, an engrossing study, it has been possible to trace all the names of paeonies used both in gardens and also in botanical literature. As this short history of paeony literature is of interest and may be useful to future students of the genus it has been included in this work as a separate chapter, since it shows how the name of each species described in this work has been arrived at. If this information had been given in the chapter where each species is described the text would have become long and involved. The best known monographs of the genus by Anderson (1817), Baker (1884), Lynch (1890) and Huth (1891) are also discussed in Chapter IV.

The cytological aspect of the genus and its relation to the geographical distribution has been referred to in Chapter II.

The late Dr. 0. Stapf, F.R.S., former Keeper of the Herbarium at the Royal Botanic Gardens, Kew, is often mentioned in this work. He was much interested in paeonies and no doubt had he lived would have brought out a monograph of the genus. We often discussed the genus and examined many species together. The Director of the Royal Botanic Gardens kindly lent me Dr. Stapf's paeony notes after his death ; these have been of the greatest value and more especially his notes on the literature of the genus.

I am most grateful to the late Sir Arthur Hill, K.C.M.G., F.R.S., Mr. A. D. Cotton, O.B.E., and all their colleagues of the Royal Botanic Gardens, Kew, for the great help they have given me ; no trouble was too much for them. Of these I should especially like to thank Mr. J. R. Sealy for all the work he has done for me in searching out the old literature and for the help he has given me in drawing up the descriptions of different species.

I am deeply indebted also to Sir William Wright Smith, Regius Keeper of the Royal Botanic Garden, Edinburgh, and to Professor H. Humbert, Director of the Musee nationale d'Histoire naturelle, Paris, for allowing me to work at their herbaria, and for their help ; and also to the Director of the John Innes Horticultural Institution, Dr. C. D. Darlington, F.R.S., and to Mr. H. N. Barber for the assistance they have so readily given me.

I should like also to put on record the great help and encouragement given me by the late Sir Daniel Hall, K.C.B., F.R.S., who took special interest in the work. Finally, I must thank Mr. F. J. Chittenden and Mr. W. T. Steam, the Librarian of the Lindley Library, for the particular help they have given me, and all the other officials of the Royal Horticultural Society, for their willing co-operation.

I am indebted to the President and Council of the Royal Horticultural Society for publishing this study, publication having been made possible through the generous bequest of £500 from Mrs. A. C. Charrington and £500 from Dame Julia M. Tilden.

F. C. STERN.