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.