HONG De-Yuan PAN Kai-Yu & XIE Zhong-Wen

Yinpingmudan. The Wild Relative of the King of Flowers. Paeonia suffruticosa Andrews

Acta Phytotaxonomica Sinica 36(6) 515-520(1998)

( Laboratory of Systematic and Evolutionary Botany, Institute of Botany, the Chinese Academy of Sciences Beijing 100093)The field work was supported by the National Geographic Society( Grant 5515-95). 1998-04-03, 1998-04-20

Abstract Paeonia suffruticosa Andrews subsp. spontanea (Rehder) S. G. Haw et L. A. Lauener ( = P. spontanea = P. jishanensis) has been considered as the wild form of widely cultivated P. suffruticosa. However, the subspecies differs from the cultivated one in shape, division and indumentum of leaves and reproductive biology. As a result of extensive field work, a form with two individuals in Yinping Shan, Caohu, Anhui, and Songxian, Henan, are found to be extremely similar to P. suffruticosa, but apparently different from P. jishanensis. The form is considered to be the wild one of P. suffruticosa and described as new: P. suffruticosa subsp. yinpingmudan Hong, K. Y. Pan et Z. W. Xie.

Key words Tree peony; Wild relative; Paeonia suffruticosa subsp. yinpingmudan

Tree peony has been cultivated for thousands of years in China, and now introduced to countries throughout the temperate region. It is called as "King of Flowers" and is a candidate of the National Flower of China. However, what is its closest wild relative is still problematic, and the taxonomy of this group should be revised. The type of Paeonia suffruticosa Andrews (Bot. Rep. 6:t. 373.1804) (Colour Plate I ) shows that it represents the tree peony widely cultivated in gardens.

Rehder(1920) described P. suffruticosa var. spontanea. From its name, he must consider it to be the wild relative of the widely cultivated tree peony. This treatment has been accepted by Stern (1946), Fang (1958) and Pan (1979). Haw and Lauener (1990) made a taxonomic revision of this group, recognizing three subspecies , i.e. P. suffruticosa subsp. suffruticosa, subsp. spontanea (Rehder)S. G. Haw et L. A. Lauener and subsp. rockii S. G. Haw et L. A. Lauener ( = Paeonia papaveracea sensu Anonymous (1972) and Pan (1979)). However, Haw and Lauener (1990) considered that subsp. suffruticosa was not derived directly from subsp. spontanea, but instead from hybridization between subsp. spontanea and subsp. rockii and subsequent backcrossing and selection.

Hong, T. and his coworkers (Hong, T. et at., 1992) described two species in this group, P. jishanensis (the type from Jishan County, Shanxi) and P. yananensis (the type from Mt. Wanhua, Yan'an, Shaanxi) in addition to raising Haw and Lauener's rockii to specific level, i.e. P. rockii (S. G. Haw et L. A. Lauener) T. Hong et J. J. Li. Two years later. Hong, T. and Osti (1994) raised spontanea to specific level, i.e. P. spontanea (Rehder) T. Hong et W. Z. Zhao, only saying "Jishan tree peony 'spontanea' is a

wild tree peony, but its cultivated offsprings have evolved into a number of cultivars, which form a group of Jishan tree peonies cultivars. Thus 'spontanea' should be treated as a species". They did not explain the relationship between P. spontanea and P. suffruticosa. At the same time, they treated P. jishanensis as a synonym of P. spontanea. Unfortunately, however, the latter is an illegitimate name.

One hundred years ago, Brühl (1896) described a new subspecies, P. moutan Ait subsp. atava Brühl (the type from "Chumbi, Tuk Chang", Yadong County, S. Xizang (Tibet )), which was late recombined into P. suffruticosa subsp. atava (Brühl) S. G. Haw and L. A. Lauener (1990). The first author of the present paper Hong (1997) came to a conclusion, after his expedition to Yadong and other places in S. Xizang in 1996, that "atava" is actually P. rockii, introduced there by lamas from the inner part of China. Introduced P. rockii could be found not only in Yadong, but also in Xigaze City, Xizang (Hong, 1997) and Bhutan (Haw and Lauener, 1990). Therefore, till now there is not any infraspecific taxon left under P. suffruticosa. A question naturally rises: what is the wild form of P. suffruticosa and how it has originated?

The first author of the present paper, Hong, chose P. suffruticosa subsp. spontanea ( = P. jishanensis T. Hong et W. Z. Zhao) as a represented research object in the "Eighth Five Years" State Key Project "Studies on Conservation Biology of Represented Endangered Plant Species in China" and made a systematic study on this taxon. Meanwhile, supported by the National Geographic Society (Grant 5515-95), he made extensive expedition to the distribution range of the woody group of Paeonia (Paeonia Sect. Moutan DC.), including S. Shanxi Province in 1993, W. Henan Province and Yan'an of Shaanxi Province in 1994, and W. Henan Province, W. Hubei Province and Mt. Taibai and Yan'an of Shaanxi Province in 1997. Pan, K. Y. and Xie, Z. W., the second and third authors of the present paper, visited Caohu and Mt. Jiuhua of Anhui Province in 1997.

Table 1 The differences between Paeonia jishanensis and P. suffruticosa

As a result of our field works, we found:

(1) P. jishanensis obviously differs from the widely cultivated cultivars in gardens, P. suffruticosa, as shown in Table 1, and thus, can not be its wild form.

(2) A shrub was found growing at the side of Mr. YANG Hui-fang's house in Secaogou village, Shigunping, Muzhijie Township, Songxian County, Henan Province. It is similar to P. suffruticosa but differs from it in single flowers and pale red-purple petals (Colour Plate 1:3). Mr. Yang, a retired country teacher, told us that he introduced the plant from a nearby mountain in early 1960's. Although it has been grown for more that 30 years, there are no vegetative plantlets developed from turions like in P. jishanensis. We visited the village twice in 1994 and 1997, when we and local people tried very hard to find it in nearby mountains without success.

(3) There is a tree peony on the cliff of Mt. Yinping in Caohu, Anhui Province. According to local people, the shrub has existed there for at least five hundreds of years. It extremely resembles P. suffruticosa and the shrub at the side of Mr. Yang's house mentioned above, except its white petals (Colour Plate 1:2. Fig. 2). We consider that the two shrubs are the real wild relative of P. suffruticosa. That is to say, the widely cultivated tree peony, P. suffruticosa, is raised from this form. Unfortunately, this form consists of only two extant individuals according to our survey, and they do not give seeds because they may be self-incompatible as in P. jishanensis (Zhou et al., 1999; Luo et al., 1998). The only one difference between P. suffruticosa and the two shrubs is whether flowers are single or double and thus the form is treated as a new subspecies.

Fig. 2 A leaf of the type of Paeonia suffruticosa subsp. yingpingmudan Hong, K. Y. Pan et Z. W. Xie

Paeonia suffruticosa Andrews subsp. yinpingmudan Hong, K. Y. Pan et Z. W. Xie, subsp. nov. TYPE: China. Anhui Province, Caohu, Mt. Yinping, 1997-04, K.Y.PAN and Z.W.XIE 9701(holotype, PE).

A subspecies typica floribus singulis differt.

As Table 1 shows, this subspecies is similar to P. suffruticosa subsp. suffruticosa in every aspect except flowers which is single in the new subspecies but double in widely cultivated one. The two individuals so far found in this new subspecies are different from each other only in flower colour, white for the one in Anhui and pale red-purple for the one in Henan. Also shown in Table 1, P. jishanensis differs from P. suffruitcosa subsp. suffruticosa in several characters and can not be the wild form of the latter as considered previously.

Henan : Songxian, Muzhijie Township, Shigunping, Secaogou, cultivated by Mr. H. F. Yang, 1997-04-28. D. Y. Hong,Y. Z. Ye and Y. X. Feng H97010(PE).

Acknowledgments We would like to thank Profs. WANG Sui-Yi and YE Yong-Zhong at Henan Agricultural University, and Dr. WANG Ying-Zhen and Miss FENG Yu-Xin for their assistance in the field work .

References

Anonymous, 1972. Icon. Cormophyt. Sin. Vol 1. Beijing: Science Press. 652, Fig. 1303

FangWP. 1958. Notes on Chinese paeonies. Acta Phytotax Sin, 7(4): 297-323

Haw S G, Lauener L A, 1990. A revision of infraspecific taxa of Paeonia suffruticosa. Edinb J Bot, 47(3):

273-281

HongDY. 1997. Paeonia (Paeoniaceae) in Xizang (Tibet). Novon. 7(2): 156-161

HongT, ZhangJX, Li J J. Zhao W Z. Li M R. 1992. Study on the Chinese wild woody peonies ( I ): new taxa of Paeonia L. Sect. Moutan DC. Bull Bot Res 12(3): 223-234

Hong T Osti G L, 1994. Study on the Chinese wild woody peonies (II): new taxa of Paeonia L. Sect. Moutan DC. Bull Bot Res, 14(3): 237-240

LuoYB, PeiYL, PanKY, Hong D Y,1998. A study on pollination biology of Paeonia suffruticosa subsp. spontanea . Acta Phytotax Sin, 36(2): 134-144

PanKY, 1979. Paeonia. In: Wang W T ed. Flora Reipublicae Popularis Sinicae. Vol 27. Beijing: Science Press. 37-59

Stern F C, 1946. A Study of the Genus Paeonia. London: Roy Hort Soc

Zhou SL, PanKY, Hong D Y. 1999. Pollination biology of Paeonia suffruticosa subsp. spontanea, with special emphasis on pollen and stigma biology. Bot J Linn Soc (in press)

Explanation of plate

Colour Plate I

1. The type of Paeonia suffruticosa Andrews (Bot. Rep. 6: t. 373. 1804);

2. The type of P. suffruticosa subsp. yinpingmudan Hong, K. Y. Pan et Z. W. Xie (K. Y. Pan and Z. W. Xie9701 (PE!));

3. P. suffruticosa subsp. yinpingmudan (Songxian, Henan, Hong, Ye and Feng H97010);

4. P. jishanensis T. Hong et W. Z. Zhao