Paeonia (Paeoniaceae) in Xizang (Tibet)

A taxonomic revision of Paeonia in Xizang is presented, and of the five species recognized, P ludlowii, P sterniana, P delavayi, P emodi, and P. veitchii, the first two are endemic. A new combination, P ludlowii (Stern & Taylor) Hong, is proposed. A considerable search for moutan var. in its type locality led to the conclusion that the taxon is rockii subsp. rockii, native of north-central China introduced to Xizang by Buddhist monks. Reproductive and other biological features of the woody ludlowii and delavayi are described. A key to species is given. Xizang (Tibet), commonly called the roof or the third pole of the world, has rather rich flora due to its diverse topographic and climatic conditions. More than 5000 species of vascular plants have been recorded in Flora Xizangica (Wu, 19811987). Five taxa of Paeonia, delavayi Franchet var. delavayi and var. lutea (Delavay ex Franchet) Finet & Gagnepain, emodi Wallich ex Royle, sterniana Fletcher, and P veitchii Lynch, have been reported from Xizang (Pan, 1979, 1985). During the preparation of monograph of Paeonia, it became apparent that the two woody taxa which were originally described from Xizang have been neglected in the Chinese literature. Paeonia moutan Aiton subsp. Brahl was described from Yadong in S Xizang (Brahl, 1896), whereas lutea Delavay ex Franchet var. ludlowii Stern & Taylor was described from Mailing County and adjacent regions in SE Xizang (Stern & Taylor, 1951, 1953). Paeonia moutan is synonym of suffruticosa, species well known in cultivation. One of the problems that needed explanation is the disjunction between the Xizang populations of P moutan subsp. and the wild forms (P suffruticosa subsp. spontanea (Rehder) S. G. Haw & L. A. Lauener) that are confined to small area in Shaanxi, Shanxi, and Henan. The second problem involves the taxonomic rank of P. lutea var. ludlowii because, according to Stern and Taylor (1953), this taxon is distinctly different from variety lutea, especially in plant height, size of flowers, and number and size of follicles. To clarify these and other problems, fieldwork was conducted in S and SE Xizang from May to June in 1996. PAEONIA MOUTAN AITON SUBSP. ATAVA BRUHL Brahl (1896) described this subspecies based on King 549 (K), which was collected from Tibet (Chumbi, Tuk Chang, June 1884). Haw and Lauener (1990) treated the plant as Paeonia suffruticosa Andreanszky subsp. atava. The wild plants of suffuticosa subsp. spontanea are confined to small area in N Henan, S Shanxi, and C Shaanxi. In fact, the whole P. suffruticosa complex (including rockii, ostii, and qiui) is confined to the Qinling Range and adjacent regions in North-central China, and none of its taxa has been recorded from Sichuan or Xizang. Several expeditions to Yadong County, where Chumbi is located, have been made since the early 1950s, but no Paeonia was found. The populations of subspecies spontanea and subspecies are isolated by more than 2000 air km and by the Qinghai-Xizang Plateau and the Himalayas. During the 1996 expedition, the present author and three assistants spent considerable time in Chumbi Valley searching for Paeonia, but none was found. An extensive search was made in nearly every plant community in the valley to 3600 m elevation. The search was also extended to other places in Yadong County from Xiayadong at 2750 m, near the border with Bhutan and Sikkim, to Shangyadong at 3200 m. The peony is famous flower in China, and wherever it exists in the wild, almost all the local people know its exact location. For example, during the expedition of 1995, inhabitants of NW Sichuan could point out the exact places where decomposita grew, and people in Mailing, Nyingchi, and Bomi counties in SE Xizang were also able to identify Lumaidao (God's flower). All 37 persons questioned indicated that no peony grows in the area. On the way back to Lhasa, single plant of rockii (S. G. Haw & L. A. Lauener) T. Hong & J. J. Li was found in front of the Zhashilenbu Temple in Xigaze City. When asked about that plant, Buddhist monk replied that it has a very long history. Paeonia rockii has two NOVON 7: 156-161. 1997. This content downloaded from 157.55.39.120 on Mon, 05 Sep 2016 03:59:42 UTC All use subject to http://about.jstor.org/terms Volume 7, Number 2 1997 Hong Paeonia in Xizang (Tibet) 157 subspecies, and Briihl's figure (t. 126) fits P. rockii subsp. rockii rather well except for the flower color. The petals of Paeonia may change color if specimens are not dried quickly. Haw and Lauener (1990) commented on specimen, Gould 132 (K), from Bhutan as having large flower with blotched petals. It appears to be closer to [P suffruticosa] subsp rockii, but the leaflets are quite frequently lobed, with up to ca. 5 rather blunt, shallow lobes per leaflet. They also considered this plant as possible escape from cultivation at lamasery, and their description fits rockii subsp rockii very well. On the basis of these findings, it is rather reasonable to say that R moutan subsp. atava is actually rockii subsp. rockii introduced to Xigaze, Yadong, and nearby Bhutan by Buddhist monks from lamaseries in the Qinling Range. KEY TO THE SPECIES OF PAEONIA IN XIZANG la. Shrubs; flowers yellow, rarely red-purple. 2a. Carpels 2-4; follicles < 4 x 1.5 cm; petals usually red-blotched at base, rarely red-purple; filaments purple-red; plants < 1.5 m tall; leaf segments and lobes mostly entire P. delavayi 2b. Carpels 1, rarely 2; follicles 4.7-7 x 2-3.3 cm; petals pure yellow; filaments yellow; plants usually 1.5-3.5 m tall; leaf segments and lobes with acuminate teeth . . . ludlowii lb. Herbs; flowers red, white, or pink. 3a. All leaflets segmented, with segments again segmented, narrowly lanceolate to lanceolate, 3.5-10 x 0.4-1.7 cm; flowers purplered P veitchii 3b. Only terminal leaflets 3-segmented, lateral ones not segmented or unequally 2-segmented, narrowly oblong or oblong-lanceolate, 9-13 X 1.2-3 cm; flowers white or rarely pinkish white. 4a. Carpels densely pubescent; flowers 3 on stem ......P emodi 4b. Carpels glabrous; flowers usually solitary P. sterniana Paeonia ludlowii (Stern & Taylor) Hong, stat. nov. Basionym: Paeonia lutea Delavay ex Franchet var. ludlowii Stern & Taylor, J. Roy. Hort. Soc. 76: 217. 1951. TYPE: China. SE Tibet [Kongbo Prov., Miling, Tsangpo Valley], Ludlow, Sherriff & Taylor 4540 (holotype, BM). Deciduous and caespitose shrubs, up to 3.5 m tall. Roots attenuate downward, not fusiform. Stems gray, up to 4 cm diam. Leaves biternate, glabrous on both sides, green above, pale glaucous beneath; petiole 9-15 cm long; leaflets 9, leaf blade 12-30 x 14-30 cm, lateral 3 leaflets on each side with main petiolules 2-3 cm long, terminal 3 leaflets with main petiolules 5-9 cm long; leaflets nearly sessile, 6-12 x 5-13 cm, usually 3-segmented nearly to base; segments 4-9 x 1.5-4 cm, mostly 3-lobed to middle; lobes 2-5 x 0.5-1.5 cm, entire or with 1 or 2 teeth, segments, lobes, and teeth all acuminate at apex. Flowers 3 or 4 on each shoot, axillary, 10-12 cm across; pedicels slightly curved, 5-9 cm long; bracts 4 or 5 and sepals 3 or 4, grade into one another; petals pure yellow, spreading, obovate, rounded at apex, 5-5.5 x 2.5-3.5 cm; filaments yellow, 1.1-1.5 cm long, anthers ca. 4 mm long; disc only 1 mm high, yellow, dentate; carpels mostly single, very rarely 2, glabrous; stigmas yellow. Follicles cylindrical, 4.7-7 x 2-3.3 cm. Seeds rounded, dark brown, ca. 1.3 cm diam. Flowering late May to early June. In their description of Paeonia lutea var. ludlowii, Stern and Taylor (1951, 1953) indicated that the taxon is distinctly different from variety lutea and distinguished it by its long, commonly unbranched stems to 8 feet (vs. to 5 feet in var. lutea), larger and more open flowers, and up to 2 carpels twice as large as those of variety lutea. Upon the examination of plants in five populations in Mailing and Nyingchi counties, as well as five populations of variety lutea (= P. delavayi), these differences have been confirmed. As shown in Figures 1 and 2, plants of P. ludlowii are tall, caespitose, and with larger, pure yellow flowers, yellow filaments, acuminate leaf segments and lobes, and mostly one carpel per flower (more than 97% of the flowers examined have single carpel and less than 3% have two). Furthermore, P. ludlowii produces very large follicles that contain the largest seeds in the genus. In contrast, plants of P. delavayi are not caespitose and have much shorter stems, acute leaf lobes and segments, more or less pendulous and smaller flowers on curved pedicels, yellow petals nearly always red-blotched at base, purple-red filaments, and 3 or 4 (rarely 2) much smaller carpels. These differences clearly support the recognition of variety ludlowii as distinct species. Paeonia ludlowii is narrow endemic of SE Xizang, where it grows in sparse forests, woods, and thickets in Nyingchi, Mailing, and Lhunze counties at 92.4?-94.80E and 28.4?-29.9?N. All five populations studied were small in size, and the largest was about 200 m in diameter. Except for the Quenima Village population (Hong et al. H96020), which had o ly four individuals, the other populations consisted of rather dense individuals, and the species was dominant element in the community. Two factors may explain the compact population with large number of individuals. First, this species has This content downloaded from 157.55.39.120 on Mon, 05 Sep 2016 03:59:42 UTC All use subject to http://about.jstor.org/terms