植物研究雑誌 J. J. Jpn. Bo t. 81:225-234(2006) 81:225-234(2006)

Pollen Pollen Morphology of Pieris D. Don (Lyonieae ，Ericaceae) and Its Taxonomic Significance

a a A. K. M. Golam SARW AR and Hideki TAKAHASHI ，b

aLaboratory aLaboratory of Systematic Botany ，Graduate School of Agriculture ，Hokkaido University ， N8 N8 W8 ，Sapporo ，060-8589 JAPAN; bThe bThe Hokkaido University Museum ， NI0 W8 ，Sapporo ，060-0810 JAPAN E-mail: E-mail: [email protected] i. ac.jp (Received (Received on November 17 ，2005)

Pollen Pollen mo 叩hology of 6 species in the genus Pieris was examined using light and scanning scanning electron microscopes. Judd's infrageneric classification of Pieris was re- examined examined in the light of new palynological characters. The genus Pieris is stenopalynous in in having 3-colporate and oblate pollen tetrads. However ，a continuous and serial varia- tion tion in the exine sculpture ，tetrad diameter ，pol 訂 and equatorial length of pollen and apocolpial apocolpial exine thickness was revealed within the genus. Pieris nana is characterized by having having the smallest pollen and the smallest rugulae in the rugulate sculpture. Considering other other distinct morphological characters ，we confirm the recognition of the monotypic subgenus subgenus Arcterica based on this species. Within the other subgenus ，Pieris ，members of the the sections Pieris and Phillyreoides can be distinguished by subtle differences in colpus width ， septum thickness and ratio of colpus length to tetrad diameter. Pieris formos αis distinguished distinguished by its psilate exine with clear secondary striate sculpture. Pieris japonica and and P. cubensis are not well differentiated in 出 e palynological characters ， and act as a bridge bridge between sec t. Pieris and sec t. Phillyreoides. On the basis of palynological charac- ters ters a dichotomous key of these taxa was also prep 訂 ed.

Key words: Pieris ， pollen morphology ， taxonomic significance.

The genus Pieris D. Don (Ericaceae- Andromedeae (Ericaceae subfamily Vac 同 Vaccinioideae-Lyonieae) Vaccinioideae-Lyonieae) (Kr on et al. 2002) cinioideae). From the phenetic standpoint ， comprises comprises seven allopatric and rather distinc- Judd (1979) did not find sufficient mo 中ho- tive tive species occurring in Eastem Asia ， logical and anatomical distinctions between Eastem America ，and Cuba (J udd 1982) and the monotypic genus Arcterica and Pieris on is is closely related to several genera in the the basis of 50 selected characters ，and tribe tribe Andromedeae sensu Stevens (1 971). treated Arcteric αnα na as an isolated species U ntil the mid of 20th century ， the generic within Pieris; P. nana (subgenus Ar cterica). limit limit of Pieris was not very well defined. This genus is considered to be a Some of its species such as P. nana ， P. monophyletic group easily separated from floribunda floribunda and P. phillyreifolia we 民 segre- related genera by a number of features; in- gated gated as distinct genera (Nuttall 1843 ，Small cluding the leaf a町 angement and anatomy ， 1914 ，1933 ，Makino 1961 ，Ohwi 1965). The timing of inflorescence development ，flower ， genus Pieris ， as circumscribed by Stevens filament and spur mo 中hology ， seed mor- (1 97 1) along with the genus Arcterica Cov. ， phology (Judd 1979 ，1982) ，chromosome is is a member of the L yonia group of the tribe number ， secondary metabolites (toxic

-225- 226 226 植物研究雑誌第81 巻第4号 平成18 年8月 diterpenes) ， and molecular characters (Kr on tions on pollen grains of Pieris have been et et al. 1999 ， 2002). However ， the infrageneric carried out previously (Yang 1952 ， Ikuse classification classification of Pieris is still in disP l! te. 1956 ，2001 ，Ueno 1962 ， Nair 1965 ，Huang Judd Judd (1 982) has divided the genus Pieris into 1972 ， Shimakura 1973 ， Nakamura 1980 ， two subgenera; the monotypic subgenus Wang et al. 1995 ，Wei 2003). Scanning elec- Arcterica Arcterica (Cov.) Judd (including P. nana) tron microscopic (SEM) observation of pol- and and subgenus Pieris ， which has been divided len grains has been made for only a single into into two sections ，sec t. Pieris (including P. species ， P. japonica (Kurosawa 1991). japonica ， P. formosa ， and P. floribundl α) ， Therefore ， the present study examines the and and sec t. Phillyreoides Benth. & Hoo k. f. pollen morphology of the genus in detail (including (including P. phillyreifolia ， P. cubensis ， and with the help of both LM and SEM to dis- P. P. swinhoe i). Recent combined phylogenetic cuss and review the present infrageneric analysis analysis of phenotypic and molecular data classification. shows that subgenus Arcterica composed of P. P. nαna is sister to the other monophyletic Materials and Methods subgenus subgenus Pieris including P. formosa ， P. The pollen of six species from the seven floribunda floribunda and P. phillyreifolia (Kr on et al. on so species in the genus Pieris was exam- 1999). 1999). But the monophyly of sec t. Pieris is ined by using LM and SEM (Table 1). not not supported in the combined analysis ， thus Polliniferous material used in this investiga- subgenus subgenus Pieris needs further study. tion was taken from dried herbarium speci- Mainly Mainly light microscopic (LM) observa- mens from the herbaria; KYO ，S ，SAPS and

Table Table 1. Voucher specimens for the palynological studies of Pieris. LM: light microscope; SEM: scanning electron microscope. microscope. Infrageneric classification follows Judd (1 982)

Taxon Collector and number Voucher information

Subgenus Subgenus Arcterica P. P. nana (Maxim.) Makino Fukuda 180 ， 181 (LM ，SEM) Japan: Honshu ，Rikuchu ， M t. Hayachine ， 19 19 June 1932 (KYO) Takahashi Takahashi & a l. 2571 (SEM) Japan: Hokkaido ， Prov. Kitami ，Monbetsu- gun ，Shirataki-mura ， M t. Hirayama ，alt. 1770 1770 m ，29 June 1982 (SAPS) Subgenus Subgenus Pieris Sec t. Pieris P. P. japonica (Thunb.) D. Don Takahashi 457 (LM ，SEM) Japan: Tokyo ， Koishikawa Bo t. Gard. ， t.， cul t.， petals pink ， 23 March 1980 (SAPS) Sasao Sasao s. n. (SEM) Taiwan: Prov. Taichu ， Kantojum ， 20 November 1931 (SAPS) P. P. koidzumiana Ohwi Sonohara 10 (LM ，SEM) Japan: Okinawa Islands ， Kunigami ， Hendona ，no date (KYO) P. P. formosa (Wall.) D. Don McLaren 32F (LM ，SEM) China: Yunnan ，Pai-ching ， 13 April 1936 (ex (ex Herb. Hort. Bo t. Reg. Edin.) (KYO) Sec t. Phillyreoides phillyreifolia P. phillyreifolia (Hook.) DC. Newcombe 267 (LM ，SEM) USA: Georgia ， Charlton Co. ， Okefenokee National National Wildlife Refuge ， 13 Sep t. 1982 (SAPT) P. P. cubensis (Griseb.) Small Ekman (P l. Ind. Occ. 16387) Cuba: Prov. Pinar del Ri o， Sierra de los (LM ，SEM) Organos ， 31 March 1923 (S) 〉ロ

m 山口回同 Nooa

Table 2. Variation in pollen characters of Pieris showing value (μm) and standard deviation. D: Tetrad diameter; P: Polar axis; E: Equatorial axis; minimum - maxi- mum values in parenthesis. Sculpture by SEM. CR: Coarsely rugulate; CRP: Coarsely rugulate-psilate; P: Psilate. Parentheses mean indistinctness

Name of Subgenus/ Colpus Apocolpial Septum Sculpture by D P E(d) D/d P厄 2f /D Section/Species Section/Species exine thickness thickness SEM Length Length (2 f) Width 旬。ロ自己。内宮司自 -E cd向 m mmiaA r cAE e r c a 也 pu 配 31. 9:t1. 4 17.1 :t1. 9 24.3 :t 2.5 1. 31 0.70 17.3 :t 2.8 2.0 :t 0.3 0.54 2.2 :t 0 .2 1.6 :t 0.3 CR* ーCR(PY*J ー* (30. 0- 34.6) :(1 4.9-20.6) (2 1.1 -30.0) (1.1 5- 1. 42) (0.64 -0 .78) (1 3.9-2 1. 6) (1. 7-2 .4) (0 .4 5-0.63) (1. 9-2 .4) (1. 2- 1. 9) Subgenus Subgenus Pieris Sec t. Pieris 20 土 33.1 :t1. 4 1. 29 20.2 :t 2.5 1.6 :t 0.6 2.4:t 0.3 CR-CR(Py*J P. P. japonica 42.8 2.4 22.0 :t1. 5 0.66 0.4 7 1.1:t 0.3 回。冨ロ〕『〈。戸∞ (39.3 -4 6.2) (1 9.5-24 .4) (3 1.4- 36.0) (1. 14-1. 41) (0.6 0-0 .74) (1 6.5-24.8) (0.7-2.5) (0.36-0.58) (2.1-3.0) (0.7-1.5) P. P. koidzumiana 39.3 :t 2.1 21. 4:t1. 6 29.7 :t1. 5 1. 32 0.72 16.9 :t 2.8 1.6 :t 0.5 0.4 3 2.6 :t 0.3 1. 7:t 0.2 CR-CRP(*J (37. 4-4 2.7) (1 9. 0- 23.5) (27.1-3 1. 2) (1. 23- 1. 40) (0.65 -0 .78) (13. 4- 20.6) (0.7- 1. 9) (0.36 -0 .54) (2.2-2.9) (1.4- 2.2) P. P. formosa 4 1. 5:t 2.6 22.1 :t1. 4 30.5 :t 2.5 1.36 0.72 13.8 :t1. 2 2.0 :t 0.3 0.33 2.1 :t 0.2 2.2 :t 0.2 p* (37.2 -4 5.6) (1 9.9-27.7) (27.8-34.8) (1. 28- 1. 45) (0.65 -0 .81 ) (1 2.5-16.8) (1. 4-2 .4) (0.27 -0.4 5) (1. 9-2 .4) (1. 9-2 .4) HZ Sec t. Phillyreoides 。・ム P. P. phillyreifoli α 48.6 士1. 6 24.3 :t 2.0 35.6 :t 2.2 1. 37 0.68 29.0 :t 2.8 0.7 :t 0.3 0.6 1. 9土0.5 1.0 :t 0 .4 CRP* (47. 0- 51. 2) (20.8-27.7) (32.2-39.6) (1. 26- 1. 49) (0.62 -0 .74) (24.8-33.0) (0.5-1.5) (0.53 -0 .64) (1. 3-2.8) (0.5- 1. 7) P. P. cubensis 39.3 :t1. 2 20.8 :t1. 0 30.7 :t1. 2 1. 28 0.68 18.6 :t1. 4 0.6 :t 0.l 0.4 7 2.3 :t 0.3 0.7 :t 0.2 CRP* (38. 0-41. 3) (19.8-22.8) (29. 4- 33.0) (1. 24- 1. 33) (0.63 -0 .72) (1 7.3-2 1. 4) (0.5 -0 .8) (0 .4 2-0.52) (2. 0- 2.8) (0.5-1.2) *Secondary *Secondary striate sculpture distinct

MMJ

可 228 228 植物研究雑誌第81 巻第4号 平成18 年8月

Table Table 3. Cumulative variance and eigen vectors of principal component analysis (PCA) using ten palynological characters characters based on LM for six species of Pieris. Character abbreviations corresponding to Table 2

Principal Principal component axis 2 3

Cumulative Cumulative variance (%) 39.926 60.622 76.138

Characters Characters Eigen vectors

D 0.4 17 0.3 36 -0.030 P 0.3 55 0.4 37 -0.149 E (d) 0.4 32 0.186 -0.297 D/d -0.024 0.3 37 0.579 P厄 -0.155 0.4 60 0.230 Colpus Colpus length (2 t) 0.4 16 -0.118 0.364 Colpus Colpus width -0 .3 63 0.067 0.110 2fID 2fID 0.228 -0.378 0.4 65 Apocolpial Apocolpial exine thickness -0.185 0.032 -0.353 Septum thickness -0.312 0.4 16 0.126

SAPT (the Botanic Garden ， Hokkaido Quantitative data of pollen morphological University ，Sapporo). features (first ten characters shown in Table Pollen Pollen was acetolysed following the tech- 2) were used for statistical calculations of nique nique of Erdtman (1 960) modified by total similarities between the pollen grains of Takahashi Takahashi (1 987). For LM ， the pollen was six species with principal component analy- mounted in silicone oil (viscosity 3000 cs) ， sis (PCA) using the Excel Stat computer and and examined and measured with a Nikon package. Eclipse Eclipse E 200 microscope. The dimensions “D" ，“ Pぺ“ E (d)" and “2f' ，co 町 esponding to Results the the tetrad diameter ， polar length ，equatorial General pollen morphology of Pieris diameter diameter and colpus length of pollen grain ， Light microscopy observations: pollen were were measured ， and the D/d ，PA and 2fID grains united at tetrahedral tetrad (Fig. 1) ， ratios ratios were calculated (see Oldfield 1959). r紅 ely other configurations ， viscin threads The measurements given in Table 2 are absent ，size medium ， or minute in P. nan α，D based based on at least 10 grains from each speci- 31.9 -4 8.6μm ，P 17.1-24.3μm ，E 24.3-35.6 men. men. Pollen size and shape classes follow 阿n，P厄 0.66 -0.72 ，oblate in shape ，ratio of Erdtman Erdtman (1 986). Pollen slides of all collec- tetrad diameter to individual grain diameter tions tions are deposited at the Hokkaido (D/d) 1.28-1 .3 7， 3-aperturate ， apertures University University Museum ，Sapporo ， Japan. For 訂 ranged according to “Fischer 乍 Law" ， SEM ， the acetolysed pollen samples were colporate ， colpi distinct (Fig. 2) ， 13.8-29.0 dehydrated dehydrated in an ethanol series ， and mounted 阿n long ， width 0.6-2.0 阿n ，ratio of colpus and and air dried on aluminum stubs from 70 % length to tetrad diameter (2f lD) 0.33-0.60 ， ethanol ， and sputter coated with Platinum- wider at middle ，somewhat obtuse to acute Palladium Palladium or Gold-Palladium by a HITACHI towards ends ，colpus m 訂 gin distinct ， ora dis- EI02 ion sputter. Subsequently the prepared tinct ，lalongate ，1. 0-3.0μm long ， width 6.4- pollen pollen was examined and photographed with 11. 0μm ， costae present but not clear in P. a JEOL JS 乱ι5310LV scanning electron mi- phillyreifolia and P. japonica ， exine tectate ， croscope croscope operated at 15 KV. Descriptive ter- apocolpial exine 1.9-2.6 阿n thick ， septum minology minology follows Punt et al. (1 994). thickness 0.7-2.2 阿n ，apocolpial exine com- August August 2006 Journal of Japanese Botany Vo l. 81 No. 4 229

Figs. Figs. 1--4. SEM rnicrographs of pollen grains in Pieris species. 1: Pollen tetrad at pol 征 view (P. formosa). formosa). 2: Pollen tetrad at equatorial view showing aperture (P. formosa). 3--4: Apocolpial exine sculpture sculpture of P. nana (Takahashi & al. 2571 and Fukuda 180 ，respectively). monly thicker than septum except P. cies occupy each distinct range ， so we can formosa with thicker septum. Exine sculp- generally compare the palynological features ture ture commonly ve 町 ucate to finely rugulate of six Pieris species in this analysis (Fig. or or rugulate in P. cubensis ， P. phillyreifolia 11). and and P japonica ， or coarsely ve 汀 ucate to co 紅 sely rugulate in P. formosa ， P. Pollen characteristics of Pi eris koidzumiana koidzumiana and P. nan α. Subgenus Arcterica (monotypic ， species SEM Observations: apocolpial exine examined: P. nana) sculpture sculpture various from coarsely rugulate to Pollen grains few in number at both LM psilate ， the rugulae with secondary sculp- slide and SEM stub. Pollen surface uneven tures; tures; faintly to finely and clearly striate and rugged ， exine sculpture coarsely (Figs. (Figs. 3-10). Exine sculpture along the colpi rugulate ， the rugulae faintly (Fig. 3) to finely similar similar to that appe 紅 ing at distal pole ， but striate (Fig. 4). In PCA ， P. nana is situated at mesocolpial mesocolpial exine having a tendency to the lower left edge of total variation of the decrease decrease in lateral extension of the rugulae Pieris pollen (Fig. 11). with with more distinct units ， colpus membrane granular granular to granuloid. Subgenus Pieris In In principal component analysis (PCA) Section Pieris (species examined: P. japon- using using the LM characters ， dots from each spe- ica ， P. koidzumiana and P. formos α) 230 230 植物研究雑誌第81 巻第4号 平成 18 年8月

Figs. Figs. 5-10. SEM micrographs of apocolpial exine sculpture in Pieris species. 5-6: P. japonica (Takahashi (Takahashi 457 and Sasao s. n. ，respectively). 7: P. koidzumiana. 8: P. formosa. 9: P. phillyrei- folia. folia. 10: P. cubensis.

Colpus Colpus membrane coarsely granulate in P. along with P. cubensis of Sec t. Phillyreifolia. japonica. japonica. Pollen surface uneven to somewhat Among the species P. formosa shows the flaf flaf and rugged ， exine sculpture coarsely highest value in the second component (Fig. rugulate ， the rugulae fain tI y to finely striate 11). in in P. japonica and P. koidzumiana (Figs. 5- 7) 7) to psilate with clearly striate sculpture in Section Phillyreoides (species examined: P. P. P. formosa (Fig. 8). In PCA ，members of this phillyreifolia and P. cubensis) section section fall in the middle of total variation ， Most grains shrink somewhat in P. August August 2006 Journal of Japanese Botany Vo l. 81 No. 4 231

Legend: Legend:

6P. nana く> P. japonica 4 • P. koidzumiana 。 oP.formosa phillyreifolia P. phillyreifolia 3 - 。 • P. cubensis 。。 2 。0 -・. 8 。 省 且 • E 0. N3 邑 。• 5 目 、 • 。。 1:1. 1:1. • 企 • • ~.<>.・ 企 A J

幽 2 1:1.1:1. 1:1.-1 A • 1:1. 1:1. 。 -3 -3 4 -3 -2 。 2 3 4 5 6 Component Component 1

Fig. Fig. 11. Two dimensional diagram of component 1 and 2 of pollen grains of six Pieris spe- cies cies based on principal component analysis using ten palynological characters. phillyreifolia. phillyreifolia. Pollen surface uneven and rug- group of closely related entities. However ， ged ， exine sculpture coarsely rugulate SEM observations show a variation in exine (-psilate) ， the rugulae loosely arranged ， and sculpture within the genus (Figs. 3-10). finely finely and clearly granulate-s 仕iate in P. There is a more or less continuous and serial phillyreifoli α(Fig. 9) or striate in P. cubensis variation in the exine sculpture from co 紅 sely (Fig. (Fig. 10). In PCA ， P. phillyreifolia is situated rugulate through co 紅 sely rugulate-psilate to at at the right edge of total variation of the psilate ，among the Pieris species. Pieris Pieris pollen which shows the highest value Pieris nana has the smallest pollen tetrad of of the first component and P. cubensis pollen (D = 31. 9 伊n) and the smallest rugulae in could could not be separated from P. japonica pol- size (compare Figs. 3-4 and 5-10). This spe- len len (Fig. 11). cies has also very distinctive morphological characters characters viz. low shrub with small ，entire Discussion Discussion and usually whorled leaves ， roughened- All All species of Pieris examined in this papillose filament ， and anthers with poorly study study have 3-colporate and oblate pollen tet- developed disintegration tissue etc. ，differing rads rads having similar rugulate to rugulate- from the other species of the genus (Judd psilate psilate (rarely psilate) exine with secondary 1982). The low number of pollen grains in striate striate sculpture ， which suggests that the both LM slide and SEM stub might be due to genus genus including P. nana is ， as a whole a the presence of poorly developed disintegra- 232 植物研究雑誌第81 巻第4号 平成18 年8月 tion tion tissue in anthers ， or all specimens might Ericaceae (Warner and Chinappa 1986). have have been collected at very late flowering These two palynological characters might be stage. stage. The distinctiveness of the P. nana pol- of special taxonomic importance in len len is also supported by PCA (l ower left Ericaceae. Distinct differences have also edge edge of total variation) using 10 been found in apocolpial exine and septum palynological palynological characters based on LM obser- thickness between the two sections (Table vations vations (Fig. 11). The PCA also indicates 2): sec t. Pieris have comparatively thicker that that among the remaining five species ， P. ja- apocolpial exine and septum (2.1-2.6 阿n ponica ， P. koidzumiana ， P. formosa and P. and 1.1-2.2 阿 ll ，respectively) than those of cubensis cubensis are relatively closer together and the sec t. Phillyreoides (1. 9-2.3μm and 0.7- situated situated at the middle of total variation ， and 1. 0μm ，respectively). P. P. phillyre グolia also has a distinct (right- Judd (1 982) considered P. japonica as a hand most) position (Fig. 11). This results of variable species; it includes a number of PCA support the division of the genus Pieris synonyms at the species level ， e. g. ， P. into into two subgenera; the monotypic subgenus popowi Palibin ， P. tα， iwanensis Hayata ， P. Arcterica Arcterica (including P. nana) and the other polita W. W. Sm. & Jeffrey ， P. koidzumiana subgenus subgenus Pieris composed of the remaining Ohwi. Pieris koidzumiana occupies the inter- species. species. The infrageneric classification of mediate space between P. japonica and P. Pieris Pieris proposed by Judd (1 982) is generally formosa in PCA (Fig. 11). But in exine supported supported by the palynological characters ， sculpture P. koidzumiana (Fig. 7) is more with with some exceptions viz. P. cubensis of similar to P. japonic α(Figs. 5-6) than P. sec t. Phillyreoides shows a closer relation- formosa (Fig. 8). Thus palynological charac- ship ship with the members of sec t. Pieris ters do not positively support the separation (especially (especially P. japonica) (Fig. 11). of P. koidzumiana from P. japonica. Judd Within Within subgenus Pieris ，P 厄 ratio shows a (1 982) also did not confirm the species status difference difference between the two sections (Table of P. koidzumiana ， because he did not find 2). 2). Section Pieris possesses a relatively any clear gap between P. koidzumian αand larger larger value (0.72) of P厄， and sec t. P. japonica in leaf shape or marginal denta- Phillyreoides Phillyreoides possesses the smaller value tion ， although he recognized some distinct (0.68) ， except for P. japonica of sec t. Pieris morphological differences between them. that that has the P厄 value 0.66 ， even lower than However ，considering other distinctions in sec t. Phillyreoides. Colpus length ， width and the morphological characters of P. ratio ratio of colpus length to tetrad diameter koidzumiana: e. g. the leaves oblanceolate (2f lD) show distinct differences among the with more blunt tip ， rachis densely species species (Table 2). Pollen grains of the sec t. puberulous ， flowers longer etc. compared to Pieris Pieris possess comparatively smaller but those of P. japonic α(Yamazaki 1993) ，it is wider wider colpus (1 3.8-20.2μm and 1.6-2.0 阿ll ， better to separate P. koidzumiana from P. respectively) respectively) compared to those of the sec t. japonica as a distinct species ， endemic to the Phillyreoides Phillyreoides (1 8.6-29.0 問II and 0.6 -0 .7μm ， Ryukyu Islands ，Japan. respectively). respectively). The 2fID value is relatively Neither the close relationships between P. smaller smaller (0.33-0 .4 7) in the sec t. Pieris ， and japonica and P. formosa ， nor P. larger larger (0 .4 7-0 .60) in the sec t. Phillyreoides. phillyreifolia with P. cubensis and P. jαpon- Distinct Distinct differences in P厄 and 2fID ratios ica ， which were found in morphological and

were were also reported previously among the sec 田 anatomical characters (J udd 1982) ， is sup- tions tions of the genus Enkianthus (Sarwar and ported by our palynological observations Takahashi Takahashi 2005) and different subfamilies of (Figs. 5-11). However ， P. japonica pollen August August 2006 Journal of Japanese Botany Vo l. 81 No. 4 233 can can not be separated from that of P. cubensis ...・... P. koidzumiana in in PCA (Fig. 11) ， and the exine sculpture is 3b. D/d 1.36 ， 2fID 0.33 ， septum thicker also also similar between. the two species (Figs. than distal exine ， septum thickness 2.2 5-6 ，10). Pieris japonica and P. cubensis act 阿n， pollen surface somewhat flat ， as as a bridge between the two sections Pieris exine sculpture psilate with clearly

and and Phillyreoides. A close relationship be- secondarily striate ...・ H ・-….. P.formosa tween tween P. formosa and P. phillyreifolia sug- 2b.2f lD 0.4 7-0.60 ， colpus width 0か 0.7 gested gested by Kr on et al. (1999) was not μm ， septum relatively thinner (0.7-1.0

supported supported by PCA (Fig. 11) ， but the distinct- 阿n) ・…...・ H ・.....・ H ・...... ・ H ・....・ H ・...・ H ・...・ H ・.5 ness ness of secondary striate sculpture is com- 5a. D/d 1.37 ， 2fID 0.60 ， septum thickness mon palynological feature between these two 1. 0μm ， the rugulae finely and clearly species species (Figs. 8-9). Under SEM ， P. formosa granulate-striate ...・ H ・. P. phillyreifolia is is readily distinguished by its psilate exine 5b. D/d 1. 28 ， 2fID 0.4 7， septum thickness with with clear secondary striate sculpture (Fig. 8) 0.7 阿n， the rugulae finely and clearly

among Pieris species. Other species have a striate ...・ H ・.....・ H ・..…...・ H ・... P. cubensis serial serial variation in the co 紅 sely rugulate- psilate psilate exine sculpture (rugulae faintly to Authors wish to express their sincere finely finely striate). Further research including the thanks to the Directors and Curators of her- study study of more specimens and combined baria: KYO ，S ，SAPS and SAPT for allow- analysis analysis of mo 中hological and molecular ing us to examine an d/ or send the specimens data data from other regions is needed to clarify on loan and sample polliniferous materials. the the relationships among the Pieris species. Particular thanks are due to M r. Toshiaki It o of of Electron Microscopy Laboratory ， Key to the species of Pieris based on Graduate School of Agriculture ，Hokkaido pollen pollen morphology University for his technical assistance and 1a. 1a. Pollen grains minute ， pollen surface un- cooperation during the SE 乱1: study and pho- even even and rugged ， exine sculpture tography of pollen grains. The first author

co 紅 sely rugulate ， the rugulae smallest (A.K .. .. P. nana Ministry of Education ， Culture ， Sports ， b. 1b. Pollen grains medial ， pollen surface un- Science and Technology (MEXT) for even even and rugged to somewhat flat ， exine Monbukagakusho Scholarship during the pe- sculpture sculpture coarsely rugulate to psilate ， the riod of this study.

rugulae rugulae relatively larger ...・ H ・...・ H ・...・ H ・..2 2a. 2a. 2fID 0.33-0 .4 7， colpus width 1. 6-2.0 References μm ， septum relatively thicker (1. 1-2.2 Erdtman G. 1960. The acetolysis method- A revised ...... μm) ...... 3 description. Svensk Bo t. Tidskr. 54: 561-564. 3a. 3a. D/d 1. 29- 1. 32 ， 2fID 0.4 3-0 .4 7 ，distal 一一一 1986. Pollen Morphology and Plant Taxonomy. exine exine thicker than septum ， septum Angiosperms. E. J. Brill ， Leiden. Huang T. C. 1972. Pollen Fl ora of Taiwan. National thickness thickness 1.1-1.7 阿n， pollen surface Taiwan University Botany Department Press. uneven uneven and rugged ， exine sculpture Ikuse M. 1956. Pollen grains of Japan. Hirokawa Pub. coarsely coarsely rugulate ， the rugulae faintly Co. ，Tokyo (in Japanese). 一一- 200 1. Pollen grains of Japan ，2nd ed. Hirokawa to to finely striate ...・ H ・.....・ H ・.....・ H ・..…… 4 4a. 4a. D/d 1. 29 ，P 厄 0.66 ， 2fID 0.4 7，sep- Pub. Co. ，Tokyo (in Japanese). Judd Judd W. S. 1979. Generic relationships in the 仰 tum thickness 1.1 n …. P. japonica Andromedeae (Ericaceae). J. Arn. Arbor. 60: 477- 4b. 4b. D/d 1.32 ，P 厄 0.72 ， 2fID 0.4 3，sep- 503. tum thickness 1.7μm. 一一一 1982. A taxonomic revision of Pieris 234 234 植物研究雑誌第81 巻第4号 平成18 年8月

(Ericaceae). (Ericaceae). J. Arn. Arbor. 63: 103-144. Sarwar A. K. M. Golam and Takahashi H. 2005. Pollen Kr on K. A.， Judd W. S. and Crayn D. M. 1999. mo 叩hology of Enkianthus Lour. (Ericaceae) and Phylogenetic Phylogenetic analysis of Andromedeae (Ericaceae its taxonomic significance. In: Abstracts of the 17th SubFam. Vaccinioideae). Amer. J. Bo t. 86: 1290- International Botanical Congress ，Vienna ，Austria ， 1300. 1300. 17-23 July 2005. p. 415. 一一一， --， Stevens P. F. ， Crayn D. M. ， Anderberg A. Shimakura M.1973. Palynomorphs of Japanese Plan t. A.， A.， Gadek P. A. Quinn C. J. and Luteyn J. L. 2002. Spec. Pu b1. Osaka Mus. Na t. His t. 5: 1-60 (in Phylogenetic Phylogenetic c1 assification of Ericaceae: molecular Japanese). and and mo 叩 evidence. hological Bo t. Rev. 68: 335- Small J. K. 1914. Ericaceae. N. Am. F1. 29: 33-103. 423. 423. 一一一 1933. Manual of the southeastern flora. Kurosawa K. 199 1. SEM Photographs of Pollen of Pu blished by the author ，New Yor k. Angiosperms. Angiosperms. Osaka Museum of Natural History ， Stevens P. F. 197 1. A c1 assification of the Ericaceae: Osaka (in Japanese). subfamilies and tribes. Bo t. J. Li nn. Soc. 64: 1-53. Makino T.196 1. Makino's new illustrated flora of Takahashi H. 1987. Pollen mo 叩hology and its taxo- Japan. Japan. Hokuryukan Co. ，Tokyo (in Japanese). nomic significance of the Monotropoideae Nair Nair P. K. K. 1965. Pollen Grains of Western (Ericaceae). Bo t. Mag. Tokyo 100: 385 -4 05. Himalayan Himalayan Plants. Asia Pub 1. House ，Bombay. Ueno J. 1962. Palynological notes on Ericaceae and Nakamura J. 1980. Diagnostic Characters of Pollen Pyrolaceae from Japan and its neighbours. Acta Grains Grains of Japan. Vo 1. 1 & 11. Osaka Museum of Phytotax. Geobo t. 20: 101-111 (in Japanese with Natural Natural History ，Osaka (in Japanese). English abstract). Nuttall Nuttall T. 1843. Description and notices of new and Wang F. ， Chien N. ，Zhang Y. and Yang H. 1995. rare rare plants in the natural orders Lobeliaceaea ， Pollen F1 0ra of China (2nd ed). Science Press ， Campanulaceae ，Vaccinieae ，Ericaceae ，collected Beijing (in Chinese). in in a journey over the continent of North America ， Warner B. G. and Chinnappa C. C. 1986. Taxonomic and and during visits to the Sandwich Islands ， and implications and evolutionary trends in Canadian Upper California. Trans. Am. Ph i1 os. Soc. n. s. 8: Ericales. CaII. J. Bo t. 64: 3113-3126. 251-272. 251-272. Wei Z. 2003. Pollen F1 0ra of Seed Plants. Yunnan Sci. Ohwi J. 1965. F1 0ra of Japan. Smithsonian Institution ， and Tech. Press ，Yunnan (in Chinese). Washington ，D. C. Yamazaki T. 1993. Pieris. In: Iwatsuki K.， Yamazaki 01dfield 01dfield F. 1959. The pollen mo 中 hology of some of T. ， Boufford D. E. ， and Ohba H. (eds.) ， Flora of the the West European Ericales. Pollen Spores 1: 19- Japan. IIIa. Kodansha ， Tokyo. 48. 48. Yang B. Y. 1952. Pollen grain mo 叩hology in the Pu nt W. ，Bl ackmore S. ， Nilsson S. and Thomas A. Le Ericaceae. Quar. J. Taiwan Mus. 5: 1-24 (in 1994. 1994. Glossary of pollen and spore terminology. Chinese). LPP Contrib. Ser. 1，LPP Found. ，Utrech t.

A. K. M. ゴラムサルワ lレa ，高橋英樹b .アセビ 属(ツツジ科ネジキ連)の花粉形態と分類学的意 義 認めることを支持する.残りのアセビ亜属 Pieris アセビ属 Pieris 約 7 種のうち 6 種の花粉形態を 内の， Pieris 節と Ph i11 yreoides 節とは溝の幅，四 光学顕微鏡と走査型電子顕微鏡で観察し， Judd の 集粒内の花粉粒間壁厚，四集粒径に対する溝長の 属内分類体系を花粉形態形質から再検討した.ア 比率で微妙な差がある . P. formosa は明瞭な二次 セビ属はステノパリナス(花粉の形態変異幅が狭 的縞模様を持った平滑型の花粉彫刻模様により識 いこと)で，偏球形の 3 溝孔粒からなる四集粒花 別される.アセビ P. japonica と P. cubensis とは 粉であった.それでも属内には，花粉壁の彫刻紋 花粉形質では十分に区別することができず， Pieris 様，四集粒径，極軸・赤道軸長，遠心極域の壁厚 節と Ph i11 yreoides 節とを結ぶ位置を占めている. において連続的な変異があった.この中でコメパ 花粉形態形質によるこれら分類群の検索表を作成 ツガザクラ P. nana は最も小さいサイズの花粉粒 した. を持ち，花粉壁のしわ紋様の単位も最小で，他の (a 北海道大学農学研究科植物体系学研究室， 明瞭な外部形態形質を考えあわせると，本種 1種 b~ じ海道大学総合博物館) からなる単型のコメバツガザクラ亜属 Arcterica を