F.C. Stern A Study of the Genus Paeonia

Section Moutan Subsection Delavayanae

delavayi group.—This group of paeonies consists of three species and their varieties found in western China and Tibet at high elevations from latitude 25° northwards to the Tsarong district in south-eastern Tibet. The group is named after Paeonia Delavayi, which was' by Pere Delavay and described by Franchet (1886).

They are all shrubs with hard woody stems with several flowers to a stem and or linear leaflets ; they are distinguished by linear to lanceolate bracts below the conspicuous fleshy discs and by being quite glabrous.

The following species and varieties are described :—

P.Delavayi Franchet 1886.

P.lutea Delavay 1886.

P.Potanini Komarov 1921

P.Potanini forma alba F. C. Stern.

P.Potanini var. trollioides F. C. Stern. .[end page 17]

These shrubby paeonies form a natural group occurring in one geographical area in western China. Forrest (1920) describes how he found these species growing on the mountains east of the Tali Lake, northwards through the Likiang range into the easternmost province of Tibet.

P.Delavayi is distributed along the limestone Likiang ranges in Yunnan at a height of 10-12,000 ft., stretching northwards to the south-west corner of Szechwan. It is a tall, shrubby paeony, unique in the shape of the bracts which make an involucre immediately below the calyx. This involucre and the colour of the flowers separate P.Delavayi from P.lutea, which is found in much the same districts, from the Tali range on limestone formations north-eastwards along the Mekong-Yangtse Divide into south-eastern Tibet. Kingdon Ward discovered P.lutea at Tsela Dzong on the Tsangpo River in Tibet (KW. 5691 in Herb. Kew) in 1924, saying it grew 6-8 ft. high, which is taller than most of the recorded plants of this species. Hanbury Tracy collected P.lutea [end page 18] (No. 200 B.M.) at Kyari Dzong in eastern Tibet at 12,500 ft. and Ludlow and Sherriff found the same species (No. 1376) at Lung Chayul in southern Tibet at 9,500 ft. These specimens are at the Herbarium of the British Museum, South Kensington.

E. H. Wilson (1913) discovered a shrubby paeony after the style of P.Delavayi but more dwarf and with smaller flowers, which was described as P.Delavayi var. angustiloba. It differs from P.Delavayi, however, in lacking the large calyx and the typical involucre and in the narrow segments of the leaves ; it also has smaller flowers and stamens of a paler colour. It is also stoloniferous. Dr. Stapf considered Wilson's plant a species distinct from P.Delavayi and suggested the name of P.angustiloba on the herbarium sheet at Kew, but Komarov (1921) had already described this plant under the name of P.Potanini. In view of the specific differences between this plant and P.Delavayi, Komarov's name of P.Potanini, which was the earlier name given to this species, has been adopted. P.Potanini has a somewhat different location to either P.Delavayi or P.lutea; it is reported from the hills around Yungning which is on the border of Yunnan in the south-west corner of Szechwan, at about 10,000 ft. going northwards near the Yalung River west of Tatsienlu in western Szechwan. There is also a white form of this species.

There is another yellow-flowered shrubby species which was collected by Monbeig in 1912 and Forrest in 1914 on the Mekong-Yangtse Divide, somewhere near Tseku. This differs from P.Potanini in its yellow flowers, which do not open wide, and are shaped more like the flower of a Trollius and also by the more erect manner of growth and by more oblong and shortly acuminate leaflets. It differs even more from P.lutea by the smaller size and shape of the flower and in having narrower and more erect segments to the leaves.

Dr. Stapf considered this plant worthy of specific rank and a description was found after his death among his papers in which he gave it the name of P.trollioides. As this plant differs from P.Potanini only in the shape and colour of the flowers I suggest that until further material can be obtained it should be considered as the variety of P.Potanini and should be called P.Potanini var. trollioides.

This group is limited to one large district of western China and Tibet; Forrest (1920) suggests that these shrubby species hybridise with each other in their native habitat and that they may do so in our gardens. The only one that has done so to my knowledge is the white form of P.Potanini, which appears to have crossed with P.Delavayi in my garden, the result being a pink-flowered form of P.Potanini, which grows in height half way between the usual height of the two species.

These species are all diploids and are no doubt closely allied to each other.Maps a-z