植 物 分 类 学 报 43(3): 210–224(2005) doi:10.1360/aps040099

Acta Phytotaxonomica Sinica http://www.plantsystematics.com

Comparative morphology of in (Parnassiaceae) from China 1, 2WU Ding 1WANG Hong 1,2LU Jin-Mei 1LI De-Zhu* 1 (Laboratory of and Plant Biogeography, Kunming Institute of Botany, the Chinese Academy of Sciences, Kunming 650204, China) 2 (Graduate School of the Chinese Academy of Sciences, Beijing 100039, China)

Abstract Epidermal characters of mature in 30 representing all the nine sections of Parnassia (Parnassiaceae) were investigated under both light microscope (LM) and scanning electron microscope (SEM). The stomata were anomocytic and existed on abaxial epidermis in all the species examined, and on the adaxial epidermis in some species. The leaf epidermal cells were usually irregular or polygonal in shape. The patterns of anticlinal walls were slightly straight, repand or sinuate. Under SEM, the inner margin of the outer stomatal rim was nearly smooth, sinuolate or sinuous, and the cuticular membrane of the leaf epidermis was striate, sometimes striate to wrinkled, occasionally granular or foveolate. Stomatal and other epidermal features in Parnassia appear to be constant within species, and thus can be used for distinguishing some species. Leaf epidermal features show that Parnassia is a quite natural . The previous reports that the stomata are anomocytic and occur only abaxially in Parnassia, yet occur both adaxially and abaxially in are not confirmed by this study, which, based on more extensive study, has shown that some species of Parnassia also exhibited stomata on both adaxial and abaxial sides. Evidence from leaf epidermis, together with that from floral anatomy and morphology as well as biogeography, suggests that section Saxifragastrum may be heterogeneous. Parnassia delavayi should be treated as a section of its own, i.e. section Xiphosandra based on morphological, cytological and leaf epidermal data. Key words Parnassia, leaf epidermis, systematic significance.

Parnassia L. is a genus of perennial herbs in wetland, consisting of over 70 species distributed in the arctic-alpine regions of the northern hemisphere, primarily in southeast and central Asia (Ku, 1987, 1995; Wu et al., 2003). The mountain ranges of southwest China and the Himalayas constitute the major centre of species diversity, and possibly also the centre of origin of this genus (Phillips, 1982; Ku, 1987) with approximately 60 species occurring there, of which about 50 are endemic to China (Ku, 1995; Gu & Hultgård, 2001; Simmons, 2004). About 10 species in Parnassia are distributed in , the second centre of species diversity of this genus (Phillips, 1982; Wu et al., 2003). The type species, P. palustris L., is the most widespread one, occurring in North America, Europe, and Asia, and south to Morocco (Korta, 1972; Phillips, 1982; Simmons, 2004). Parnassia is a fairly homogeneous genus with unique external morphological characters, i.e., solitary, terminal, bisexual and pentamerous with antipetalous . However, its systematic position has long been in dispute. Although Parnassia was treated as a of its own, Parnassiaceae (Gray, 1821) was not commonly recognized until

——————————— Received: 20 August 2004 Accepted: 10 January 2005 Supported by the National Program for R & D Infrastructure and Facility Development (2004DKA30430)), and the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. KSCX2-10106B). * Author for correspondence. E-mail: . No. 3 WU Ding et al.: Leaf epidermis in Parnassia (Parnassiaceae) 211

Hutchinson (1969), Thorne (1983), Dahlgren (1983) and Takhtajan (1969, 1997). It has long been often treated as a subfamily of (Engler, 1930; Thorne, 1976; Dahlgren, 1980; Cronquist, 1981; Ku, 1987, 1995; Gu & Hultgård, 2001). Sometimes Parnassia was included in Parnassioideae in Droseraceae (Drude, 1875; Pace, 1912; Arber, 1913), and thought to be closely related to Hypericaceae (Arber, 1913; Jay, 1971), or even Nymphaeaceae (Hallier, 1901). Recent molecular systematic studies have revealed that Parnassiaceae, including Parnassia and Lepuropetalon Ell., is a sister group of (Chase et al., 1993; APG, 1998; Soltis et al., 2000; Savolainen et al., 2000; APG II, 2003). Drude (1875) recognized four sections within Parnassia based on characteristics of the staminodes, position, and carpel number, i.e. sect. Nectarodroson, sect. Fimbripetalum, sect. Nectarotrilobos and sect. Saxifragastrum. Based on the connective elongation of the fertile anthers, the genus was divided into two sections by Franchet (1897), i.e. sect. Xiphosandra and sect. Amblysandra.. Mainly following Drude’s classification, Engler (1930) added a fifth section, i.e. sect. Cladoparnassia, and this was followed by Handel-Mazzetti (1941). Phillips (1982) studied the species of Parnassia in North America, and established a new section, sect. Longiloba. In the course of preparing an account for the Flora of China, Ku (1987) made a revision of the Chinese Parnassia, and divided the Chinese species into nine sections, i.e. sect. Saxifragastrum, sect. Cladoparnassia, sect. Odontohymen, sect. Nectaro- trilobos, sect. Nectarobilobos, sect. Allolobos, sect. Fimbripetalum, sect. Nectaroquinquelo- bos and sect. Parnassia. This was adopted in the Flora of China (Gu & Hultgård, 2001). In their analysis of biogeographic patterns of families and genera of plants of China, Wu et al. (2003) treated Ku’s section Nectaroquinquelobos as a synonym of section Allolobos, but recognized Franchet’s section Xiphosandra. Leaf epidermal characteristics are of potential taxonomical importance (Jones, 1986; Baronova, 1992). However, the leaf epidermis of the Parnassia species has been little studied (Gornall & Al-Shammary, 1998). This is no exception for China, a centre of distribution of Parnassia. This paper, as part of a monographic study of this genus in China, is to report the leaf epidermal features of 30 species from China, of which 16 are endemic to China, and 28 are investigated for the first time with respect to their leaf epidermis. 1 Material and Methods For practical reason, the sectional system of classification of Ku (1995) was followed. Mature leaves of 30 species from China, representing all the nine sections within the genus, were investigated under light microscope (LM) and scanning electron microscope (SEM). Most samples were obtained from the field in China’s southwestern part (Yunnan, Sichuan and Guizhou) and northwestern part (Xinjiang), with a few from the Herbarium of the Kunming Institute of Botany (KUN). All voucher specimens were deposited in KUN (Table 1). Samples were taken from mature leaves. The materials for LM study were boiled in water before being macerated in Jeffrey’s solution (Stace, 1965). Pieces of leaf epidermis were stained in a solution of 1% safranin (in 50% alcohol) before being mounted in glycerine jelly. To check the constancy of epidermal structure, at least five slides were made from different parts of a single leaf or from different leaves of the same species. The stomatal index was calculated using formula S/(E+S)×100%. The materials for SEM observation were directly mounted on stubs without any treatment, and sputter coated with gold-palladium. Observations were made using a KYKY-10000B (Science Instrument Company, Beijing) electronic microscope at 15 kV. Descriptive terminology of leaf epidermis follows Wilkinson (1979). 212 Acta Phytotaxonomica Sinica Vol. 43

Table 1 Species, localities and vouchers used for the leaf epidermal studies in Parnassia Taxon Locality Voucher sect. Saxifragastrum P. esquirolii Lévl. Yiliang, Yunnan D. Wu et al. 0313 P. longipetala Hand.-Mazz. Weixi, Yunnan C. W. Wang 0208834 P. longipetaloides J. T. Pan Lijiang, Yunnan. D. Wu et al. 0305 P. tenella Hook. f. & Thoms. Zhongdian, Yunnan D. Wu 0366 P. yunnanensis Franch. Dêqên, Yunnan H. Wang et al. 03066 sect. Cladoparnassia P. faberi Oliv. Mt. Emeishan, Sichuan D. Wu 0217 sect. Odontohymen P. farreri W. E. Evans Gongshan, Yunnan L. M. Gao et al. 0319 sect. Nectarotrilobos P. cacuminum Hand.-Mazz. Dali, Yunnan D. Wu et al. 0326 P. chinensis Franch. Dali, Yunnan D. Wu et al. 0203 P. delavayi Franch. Lijiang, Yunnan D. Wu 0204 P. epunctulata J. T. Pan Qiaojia, Yunnan H. Wang et al. 03890 P. laxmanni Pall. Mt.Tianshan, Xinjiang D. Wu et al. 0331 P. mysorensis Heyne ex Wight & Arn. Qiaojia, Yunnan D. Wu 0210 P. mysorensis var. aucta Diels Dêqên, Yunnan D. Wu 0201 P. pusilla Wall. ex Arn. Zhongdian, Yunnan D. Wu et al. 03028 P. scaposa Mattf. Dali, Yunnan J. P. Yue 030300 P. submysorensis J. T. Pan Zhongdian, Yunnan H. Wang et al. 0312 P. trinervis Drude Nyingchi, Xizang H. Y. Ma 03081 P. venusta Jien Qiaojia, Yunnan D. Wu et al. 0211 P. viridiflora Batalin Dêqên, Yunnan H. Wang et al. 03065 P. yui Jien Gongshan, Yunnan L. M. Gao et al. 2327 sect. Nectarobilobos P. bifolia Nekrass. Mt. Tianshan, Xinjiang D. Wu et al. 0329 sect. Allolobos P. wightiana Wall. ex Wight & Arn. Gongshan, Yunnan L. M. Gao et al. 2318 P. monochorifolia Franch. Qiaojia, Yunnan H. Wang et al. 031082 sect. Fimbripetalum P. amoena Diels Wenchuan, Sichuan D. Wu 0215 P. foliosa Hook. f. & Thoms. Jinan, Jiangxi J. S. Xiong 97380 P. noemiae Franch. Mt. Jinfoshan, Chongqing D. Wu 0218 sect. Nectaroquinquelobos P. gansuensis T. C. Ku Zhongdian, Yunnan D. Wu 0209 P. perciliata Diels Mt. Fanjingshan, Guizhou L. M. Gao et al. 03353 sect. Parnassia P. palustris L. Hejing, Xinjiang A. J. Li et al. 0208956

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2 Results The characteristics of leaf epidermis in Parnassia under LM and SEM are summarized in Table 2 and Table 3. Stomatal and other epidermal features appear to be constant within species and thus may be of systematic significance. 2.1 Characteristics of leaf epidermis under LM 2.1.1 Epidermal cells The form of epidermal cells in Parnassia was usually polygonal or irregular. The shapes of epidermal cells of the same species were different on the adaxial (Ad) and abaxial (Ab) sides in most species. Some species have similar epidermal cells between the Ad and Ab sides, such as P. amoena (Ad and Ab, Figs. 17, 39), P. faberi (Ad and Ab, Figs. 18, 43), P. bifolia (Ad and Ab, Figs. 19, 36), P. yunnanensis (Ad and Ab, Figs. 20, 45), P. venusta (Fig. 21) and P. laxmanni (Fig, 22). In about 2/3 of the total of species studied, the shape of the adaxial epidermal cells was usually polygonal. The form of the abaxial epidermal cells was irregular in all the species except in P. monochorifolia (Fig. 23). The patterns of anticlinal walls of epidermal cells were slightly straight, repand or sinuate. The pattern of anticlinal cells may vary in different species or between Ad and Ab epidermis of the same species, and the undulation of anticlinal walls was usually stronger on the abaxial side and fell into three types, viz., the straight to arched type, which occurred in P. submysorensis (Ad, Fig. 1), P. delavayi (Ad, Fig. 2), P. chinensis (Ad, Fig. 3), P. yui (Ad, Fig. 4), P. tenella (Ad, Fig. 5), P. esquirolii (Ad, Fig. 6), P. noemiae (Ad, Fig. 7), P. perciliata (Ad, Fig. 8), P. monochorifolia (Ad and Ab, Figs. 9, 23), P. farreri (Ad, Fig. 10), P. palustris (Ad, Fig. 11) and P. gansuensis (Ad, Fig. 12); the slightly undulate (or repand) type, which occurred in P. longipetaloides (Ad, Fig. 13), P. cacuminum (Ad and Ab, Figs. 14, 24), P. epunctulata (Ad, Fig. 15) and P. wightiana (Ad, Fig. 16); and the strongly sinuous type, which occurred in P. amoena (Ad and Ab, Figs.17, 39), P. faberi (Ad and Ab, Figs. 18, 43), P. bifolia (Ad and Ab, Figs. 19, 36), P. yunnanensis (Ad and Ab, Figs. 20, 45), P. venusta (Ad, Fig. 21), P. laxmanni (Ad, Fig. 22), P. mysorensis (Ab, Fig. 25), P. longipetala (Ab, Fig. 26), P. tenella (Ab, Fig. 27), P. yui (Ab, Fig. 28), P. trinervis (Ab, Fig. 29), P. scaposa (Ab, Fig. 30), P. viridiflora (Ab, Fig. 31), P. pusilla (Ab, Fig. 32), P. mysorensis var. aucta (Ab, Fig. 33), P. palustris (Ab, Fig. 34), P. perciliata (Ab, Fig. 35), P. foliosa (Ab, Fig. 37), P. noemiae (Ab, Fig. 38), P. gansuensis (Ab, Fig. 40), P. wightiana (Ab, Fig. 41), P. farreri (Ab, Fig. 42) and P. esquirolii (Ab, Fig. 44). 2.1.2 Stomatal apparatus Stomata in all species studied were anomocytic. Stomata existed on the abaxial epidermis in all species, but were absent on the adaxial epidermis in most species. Of all the materials observed, stomata were found on both adaxial and abaxial sides in seven species, viz., P. bifolia (Fig. 19), P. esquirolii (Fig. 6), P. faberi (Fig. 18), P. palustris (Fig. 11), P. tenella (Fig. 5), P. trinervis (Fig. 29) and P. yunnanensis (Fig. 45). The size of stomata was (32.2-56.8)×(27.5-50.2) µm. The species in sect. Fimbripeta- lum had larger stomata than those of other sections. For example, the stomata in P. noemiae were obviously larger than those in P. chinensis and P. cacuminum. The stomatal density was also different among species. The stomatal index ranged from 37.5% in P. monochorifolia, with the stomata being densely distributed, to 11.6 % in P. venusta, with the stomata being sparsely distributed. Furthermore, stomata of the adaxial epidermis were smaller and sparser than those of the abaxial side. 2.2 Characteristics of leaf epidermis under SEM 2.2.1 Guard cells The outlines of the pair of guard cells were usually suborbiculate to widely elliptic as seen in surface view, with length/width (L/W) ratio 1.1-1.5:1. Guard cells often thickened to a certain extent, and were made up of outer stomatal ledges or rims. Three types of the rim of outer stomatal ledge or rim were observed: nearly smooth, sinuolate to erose, and sinuous. 214 Acta Phytotaxonomica Sinica Vol. 43

Table 2 The characters of leaf epidermis of Parnassia under LM Taxon Adaxial epidermis Abaxial epidermis Figure Shape of Pattern of Shape of Pattern of Size of Stomatal cells anticlinal ordinary anticlinal stomata index walls cells walls (µm2) sect. Saxifragastrum P. esquirolii Pol Str-arc Irr Sin 47.2×39.0 22.7 6, 44 P. longipetala Pol Str-arc Irr Rep 41.6×34.5 16.9 26 P. longipetaloides Irr Rep Irr Sin 41.5×36.6 23.1 13 P. tenella Pol Str-arc Irr Sin 56.6×49.0 15.6 5, 27 P. yunnanensis Irr Sin Irr Sin 47.9×34.2 28.9 20, 45 sect. Cladoparnassia P. faberi Irr Sin Irr Sin 47.3×46.9 20.7 18, 43 sect. Odontohymen P. farreri Pol Str-arc Irr Sin 42.8×35.1 19.4 10, 42 sect. Nectarotrilobos P. cacuminum Irr Rep Irr Rep 32.8×29.2 14.7 14, 24 P. chinensis Pol Str-arc Irr Rep 32.2×29.1 29.4 3 P. delavayi Pol Str-arc Irr Sin 47.8×41.6 27.8 2 P. epunctulata Irr Rep Irr Sin 35.2×31.9 18.2 15 P. laxmanni Irr Sin Irr Sin 40.1×36.7 17.9 22 P. mysorensis Pol Str-arc Irr Rep 42.9×37.8 23.7 25 P. mysorensis var. aucta Pol Str-arc Irr Sin 41.9×34.8 28.6 33 P. pusilla Pol Str-arc Irr Sin 34.5×28.2 31.1 32 P. scaposa Pol Str-arc Irr Sin 43.5×32.8 31.2 30 P. submysorensis Pol Str-arc Irr Sin 41.1×33.2 24.2 1 P. trinervis Pol Str-arc Irr Sin 38.0×33.3 20.7 29 P. venusta Irr Sin Irr Sin 42.6×33.8 11.6 21 P. viridiflora Pol Str-arc Irr Sin 44.9×37.7 15.4 31 P. yui Pol Str-arc Irr Sin 40.7×34.1 14.3 4, 28 sect. Nectarobilobos P. bifolia Irr Sin Irr Sin 54.5×47.3 13.3 19, 36 sect. Allolobos P. wightiana Irr Rep Irr Sin 44.2×36.5 27.3 16, 41 P. monochorifolia Pol Str-arc Pol Str-arc 37.2×34.8 37.5 9, 23 sect. Fimbripetalum P. amoena Irr Sin Irr Sin 48.5×41.8 22.7 17, 39 P. foliosa Pol Str-arc Pol Str-arc 40.0×33.7 37.2 37 P. noemiae Pol Str-arc Irr Sin 56.8×50.2 21.1 7, 38 sect. Nectaroquinquelobos P. gansuensis Pol Str-arc Irr Sin 38.7×27.5 34.4 12, 40 P. perciliata Pol Str-arc Irr Sin 48.9×33.2 19.5 8, 35 sect. Parnassia P. palustris Pol Str-arc Irr Sin 40.3×37.8 19.6 11, 34 Irr=irregular; Pol=polygonal; Str-arc=straight to arched; Rep=repand; Sin=sinuous.

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Table 3 The characters of leaf abaxial epidermis of Parnassia under SEM Shape of guard Inner margin of outer Taxon Cuticular membrane Figure cells stomatal rim sect. Saxifragastrum P. esquirolii striate and wrinkled widely elliptic sinuous 68 P. longipetala striate widely elliptic sinuolate to erose P. longipetaloides striate and wrinkled widely elliptic sinuous 67 P. tenella striate widely elliptic sinuolate to erose 64 P. yunnanensis striate and wrinkled widely elliptic sinuolate to erose 66 sect. Cladoparnassia P. faberi striate and wrinkled suborbiculate nearly smooth 49 sect. Odontohymen P. farreri striate widely elliptic nearly smooth 50, 51 sect. Nectarotrilobos P. cacuminum striate widely elliptic sinuolate to erose P. chinensis striate widely elliptic sinuolate to erose 60 P. delavayi striate widely elliptic nearly smooth 58 P. epunctulata striate widely elliptic sinuolate to erose P. laxmanni striate and wrinkled widely elliptic nearly smooth 57 P. mysorensis striate and granular widely elliptic sinuolate to erose 62 P. mysorensis var. aucta striate widely elliptic sinuolate to erose P. pusilla striate widely elliptic sinuolate to erose P. scaposa striate and wrinkled widely elliptic nearly smooth P. submysorensis striate widely elliptic sinuous 69 P. trinervis striate widely elliptic nearly smooth 54 P. venusta striate and wrinkled widely elliptic sinuolate to erose P. viridiflora striate and wrinkled suborbiculate sinuolate to erose P. yui striate widely elliptic nearly smooth sect. Nectarobilobos P. bifolia striate and wrinkled widely elliptic nearly smooth 52, 53 sect. Allolobos P. wightiana striate suborbiculate nearly smooth 48 P. monochorifolia striate and foveolate widely elliptic sinuolate to erose 61 sect. Fimbripetalum P. amoena striate widely elliptic nearly smooth P. foliosa striate widely elliptic sinuolate to erose 63 P. noemiae striate widely elliptic nearly smooth 55, 56 sect. Nectaroquinquelobos P. gansuensis striate widely elliptic nearly smooth 46, 47 P. perciliata striate and wrinkled widely elliptic nearly smooth 59 sect. Parnassia P. palustris striate and wrinkled widely elliptic sinuolate to erose 65

216 Acta Phytotaxonomica Sinica Vol. 43

Figs. 1-15. Characteristics of adaxial epidermal cells (LM). 1-12. Polygonal cells with straight anticlinal walls. 1. Parnassia submysorensis. 2. P. delavayi. 3. P. chinensis. 4. P. yu i. 5. P. tenella. 6. P. esquirolii. 7. P. noemiae. 8. P. perciliata. 9. P. monochorifolia. 10. P. f a r rer i. 11. P. palustris. 12. P. gansuensis. 13-15. Irregular cells with repand anticlinal walls. 13. P. longipetaloides. 14. P. cacuminum. 15. P. epunctulata. Scale bar=50 µm. No. 3 WU Ding et al.: Leaf epidermis in Parnassia (Parnassiaceae) 217

Figs. 16-30. Characteristics of epidermal cells (LM). 16. Irregular cells with repand anticlinal walls, Parnassia wightiana (Ad). 17-22. Irregular cells with sinuous anticlinal walls, all Ad. 17. P. amoena. 18. P. faberi. 19. P. bifolia. 20. P. yunnanensis. 21. P. venusta. 22. P. laxmanni. 23. Polygonal cells with straight anticlinal walls, P. monochorifolia (Ab). 24-26. Irregular cells with repand anticlinal walls, all Ab. 24. P. cacuminum. 25. P. mys o ren s i s . 26. P. longipetala. 27-30. Irregular cells with sinuous anticlinal walls, all Ab. 27. P. tenella. 28. P. yui. 29. P. trinervis. 30. P. scaposa. Scale bar=50 µm. 218 Acta Phytotaxonomica Sinica Vol. 43

Figs. 31-45. Characteristics of epidermal cells (LM). Irregular cells with sinuous anticlinal walls, all Ab. 31. Parnassia viridiflora. 32. P. pusilla. 33. P. mysorensis var. aucta. 34. P. palustris. 35. P. perciliata. 36. P. bifolia. 37. P. foliosa. 38. P. noemiae. 39. P. amoena. 40. P. gansuensis. 41. P. wightiana. 42. P. farreri. 43. P. faberi. 44. P. esquirolii. 45. P. yunnanensis. Scale bar=50 µm. No. 3 WU Ding et al.: Leaf epidermis in Parnassia (Parnassiaceae) 219

Figs. 46-57. Characteristics of epidermal surface under scanning electron microscopy (SEM), all Ab. Nearly smooth of the inner margin of the outer stomatal rim. 46, 47. Parnassia gansuensis. 48. P. wightiana. 49. P. faberi. 50, 51. P. f a r rer i. 52, 53. P. bifolia. 54. P. trinervis. 55, 56. P. noemiae. 57. P. laxmanni. Scale bar=10 µm. 220 Acta Phytotaxonomica Sinica Vol. 43

Figs. 58-69. Characteristics of epidermal surface (SEM), all Ab. 58, 59. Nearly smooth of the inner margin of the outer stomatal rim. 58. Parnassia delavayi. 59. P. perciliata. 60-66. Sinuolate to erose of the inner margin of the outer stomatal rim. 60. P. ch i n e n s i s . 61. P. monochorifolia. 62. P. mys o ren s i s . 63. P. foliosa. 64. P. tenella. 65. P. palustris. 66. P. yunnanensis. 67-69. Sinuous of the inner margin of the outer stomatal rim. 67. P. longipetaloides. 68. P. esquirolii. 69. P. submysorensis. Scale bar=10 µm. No. 3 WU Ding et al.: Leaf epidermis in Parnassia (Parnassiaceae) 221

The first type with nearly smooth inner margin of the outer stomatal rim was found to occur in 13 species, such as P. gansuensis (Figs. 46, 47), P. wightiana (Fig. 48), P. faberi (Fig. 49), P. farreri (Figs. 50, 51), P. bifolia (Figs. 52, 53), P. trinervis (Fig. 54), P. noemiae (Figs. 55, 56), P. laxmanni (Fig. 57), P. delavayi (Fig. 58) and P. perciliata (Fig. 59). The type with sinuolate to erose inner margin of the outer stomatal rim may represent an interme- diate one, which was found to occur in 14 species, such as P. chinensis (Fig. 60), P. mono- chorifolia (Fig. 61), P. mysorensis (Fig. 62), P. foliosa (Fig. 63), P. tenella (Fig. 64), P. palustris (Fig. 65) and P. yunnanensis (Fig. 66). The sinuous type existed in three species, i.e. P. longipetaloides (Fig. 67), P. esquirolii (Fig. 68) and P. submysorensis (Fig. 69). Strikingly tall, upright outer stomatal rims occurred in all species, except in P. delavayi, in which the stomatal rims were almost at the same level with or slightly lower than the epidermis. Furthermore, the cuticular thickening of the common wall between the guard cells was found in some species, such as P. viridiflora (Fig. 31), P. bifolia (Ab, Fig. 36), P. gansuensis (Ab, Fig. 40), P. esquirolii (Ab, Fig. 44) and P. yunnanensis (Ab, Fig. 45). 2.2.2 Cuticular membrane Hairs were absent on both Ad and Ab of the species investigated. The cuticular membrane of the leaf epidermis was striate, sometimes striate to wrinkled, occasionally granular or foveolate. Based on the characters observed on the abaxial epidermis, three types of the cuticular membrane were found, viz., Type I, smooth to weakly undulate type,which occurred in P. gansuensis (Fig. 46), P. wightiana (Fig. 48), P. trinervis (Fig. 54), P. delavayi (Fig. 58) and P. submysorensis (Fig. 69); Type II, striate to wrinkled type, which occurred in P. faberi (Fig. 49), P. bifolia (Fig. 52), P. laxmanni (Fig. 57), P. palustris (Fig. 65), P. yunnanensis (Fig. 66), P. longipetaloides (Fig. 67) and P. esquirolii (Fig. 68); and Type III, striations with granular or foveolate type, which occurred in P. mysorensis (Fig. 62) and P. monochorifolia (Fig. 61). 3 Discussion The species observed covered all sections and subsections of Parnassia in Ku’s (1987, 1995) system of classification of the genus. It was shown that the stomata were anomocytic and existed on abaxial epidermis of all species. This was in consensus with the previous reports (Gornall & Al-Shammary, 1998). With the exception of P. monochorifolia, the form of epidermal cells was irregular on the abaxial side. The cuticular membrane of the leaf epidermis was generally striate. The leaf epidermal features among species were fairly similar to each other. The features of leaf epidermal showed that Parnassia was a quite natural genus. Stomata have been previously reported to be anomocytic and only abaxial in Parnassia, yet both adaxial and abaxial in Lepuropetalon (Gornall & Al-Shammary, 1998). This study, which is based on more extensive sampling, has shown that many taxa in the genus Parnassia did have stomata only on the abaxial side, but some species had stomata on both Ad and Ab sides. The species with adaxial stomata were P. bifolia, P. esquirolii, P. faberi, P. palustris, P. tenella, P. trinervis and P. yunnanensis, although the stomata were smaller and inconspicu- ous. The character of the presence of stomata on both sides occurred in different groups not very closely related, indicating that this character might not have a single origin. P. bifolia, a very distinct species with 2-lobed flat staminodes and two cauline leaves, was treated as a section of its own, sect. Nectarobilobos (Ku, 1987, 1995; Wu et al., 2003). Leaf epidermal features of this species were also distinctive. The stomata occurred on both sides. The form of the leaf epidermal cells was considerably similar on the Ad and Ab sides, and belonged to the irregular type. The cuticular thickening of the common wall between the guard cells was also present in P. bifolia. These features support the segreation of the monotypic section Nectaro- bilobos. 222 Acta Phytotaxonomica Sinica Vol. 43

In Parnassia, the leaf epidermal cells varied in shape, and diversified in the patterns of anticlinal walls, especially so on the abaxial side. These variations correlated to a certain extent with the gross morphology, palynology and biogeography in the genus. There are eight species in sect. Saxifragastrum, four of which, i.e. P. tenella, P. longipetala, P. longipeta- loides and P. yunnanensis, were studied here. This section is characterized by having terete, apically entire, rounded or discoid staminodes. On the abaxial side, the shape of epidermal cells in P. tenella was polygonal, while irregular in P. yunnanensis. The patterns of anticlinal walls varied in different species. The anticlinal walls were straight to arched in P. tenella, slightly undulate (or repand) in P. longipetaloides, and strongly sinuous in P. yunnanensis. The pollen morphology is inconstant within sect. Saxifragastrum. P. tenella is of foveolate reticulate exine sculpture of pollen while P. longipetala and P. yunnanensis are of coarsely reticulate exine sculpture of pollen (Wu et al., 2005). In addition, the section is restricted in southwest China in distribution, and each species is highly restricted in distributional range (Phillips, 1982). All species in the section are distributed in higher altitudinal zones of the Himalayan-Hengduan Mountains region (Wu et al., 2003), which is considered as one of the world’s “hot spots” of biodiversity (Myers, 1988; Myers et al., 2000). Evidence from leaf epidermis, just as that from floral anatomy and pollen morphology as well as geographical distribution, suggests that this section may still be in active differentiation, and may be a heterogeneous group. The results of our study show that the characteristics of the leaf epidermis can provide some anatomical evidence for the classification of Parnassia. Parnassia wightiana is the most widespread species of the genus in Asia, occurring from northeast India to the Himalayan- Hengduan Mountains region, and to south-central mountains of China (Wu et al., 2003). Morphologically, it is also a highly variable species, and the intermediate forms occur in various regions (Ku, 1987; Gu & Hultgård, 2001; Wu et al., 2003). Ku (1987) described the populations from southern Gansu as a new species, P. gansuensis. The characteristics of leaf epidermis support this treatment. The shape of the leaf epidermal cells in P. wightiana was repand while in P. gansuensis it was straight to arched on the Ad side. The stomatal density was also different between the two species, with the stomatal index in P. gansuensis being 34.4%, while 27.3% in P. wightiana. In addition, the cuticular thickening of the common wall between the guard cells was present in P. gansuensis, but absent in P. wightiana. Both mor- phological and leaf epidermal features indicate that P. gansuensis should be a good species. The cuticular membrane of the leaf epidermis in all the species studied was striate, sometimes striate to wrinkled, occasionally granular or foveolate. The characters of the cuticular membrane of the leaf epidermis could serve as a criterion of distinguishing some species in the genus, for example P. mysorensis and P. monochorifolia. The former had striate, granular cuticular membrane while the latter had striate, foveolate cuticular membrane. Parnassia delavayi has 3-lobed staminodes, and has been placed in sect. Nectarotrilobos (Drude, 1875; Engler, 1930; Handel-Mazzetti, 1941; Ku, 1987, 1995). Cytological studies have revealed some variation in the basic chromosome numbers of the genus Parnassia (Funamoto et al., 1998, 2001). The chromosome number is 2n=14 with x=7 in P. delavayi, rather than 2n=18 with x=9 and 2n=16 with x=8 as in other species. The epidermal features as revealed in this study have shown that P. delavayi is quite unique in the genus by having stomatal rims which were almost at some level with or slightly lower than the epidermis. On the contrary, all the other species had conspicuously tall and upright outer stomatal rims. Geographically, P. delavayi is restricted to China and the Himalayas. Morphologically, its anther connectives elongate beyond the anther sacs. Based on the connective elongation of the fertile anthers, the genus Parnassia was divided into two sections by Franchet (1897). Therefore, evidence from morphology, leaf epidermis and cytology strongly suggested that P. delavayi No. 3 WU Ding et al.: Leaf epidermis in Parnassia (Parnassiaceae) 223 should be treated as a section of its own, i.e. sect. Xiphosandra (Franchet, 1897). This treatment has also been supported by the biogeographic analysis performed by Wu et al. (2003). 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中国梅花草属植物的叶表皮特征及其系统学意义 1, 2吴 丁 1王 红 1卢金梅 1李德铢* 1(中国科学院昆明植物研究所 昆明 650204) 2(中国科学院研究生院 北京 100039) 摘要 利用光学显微镜和扫描电镜对梅花草属Parnassia 30种植物的叶表皮进行了观察。结果表明:气孔 器普遍存在于叶的下表皮,少数种的上表皮也有分布,均为无规则型。叶表皮细胞形状为多边形或不规则 形;垂周壁式样可区分为近平直、浅波状和波状。在扫描电镜下,叶表皮气孔器外拱盖内缘为近平滑、浅波 状或波状;一些种的保卫细胞两端有加厚;角质膜条纹状,有的条纹隆起,有的条纹上附有颗粒或小孔穴。 气孔器类型及下表皮细胞形状的一致性表明梅花草属是一个自然分类群;sect. Saxifragastrum叶表皮特 征具有多样性显示该组可能是一个复合群;突隔梅花草P. delavayi属于subsect. Xiphosandra,其气孔下陷, 与其细胞学特征相似,支持独立为一组;此外,气孔器的分布、保卫细胞两端加厚、气孔器外拱盖内缘形态 以及角质膜等特征对该属部分种的区分有一定的参考价值。 关键词 梅花草属; 叶表皮; 系统学意义