Flora 206 (2011) 458–467 Contents lists available at ScienceDirect Flora journal homepage: www.elsevier.de/flora Pollen morphology of Chinese Curcuma L. and Boesenbergia Kuntz (Zingiberaceae): Taxonomic implications Juan Chen a,b, Nian-He Xia a,∗ a Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, The Chinese Academy of Sciences, No. 723, Xingke Road, Tianhe District, Guangzhou 510650, People’s Republic of China b Graduate University of Chinese Academy of Sciences, Beijing 100049, People’s Republic of China article info abstract Article history: In order to find new non-molecular evidence to support the phylogenetic and taxonomic position, pollen Received 23 March 2010 grains of 20 populations of 16 species of Chinese Curcuma L. and Boesenbergia Kuntz (Zingiberaceae) Accepted 19 September 2010 were investigated under SEM and TEM. The pollen grains are spherical and ovoid, nonaperturate. The pollen wall is composed of a very thin exine and a thick intine. The exine is psilate or echinate. The Keywords: intine consists of two layers, i.e., a thick, channeled layer (exintine) and an inner homogenous layer Curcuma (endintine). The results reveal morphological congruence between the pollen grains of species of Curcuma, Boesenbergia which according to DNA sequence data appears to be a polyphyletic genus. However the uniform pollen Zingiberaceae Pollen morphology morphology in Curcuma provides no evidence to divide this genus into separate taxonomic entities. Our results on pollen morphology also do not provide any additional evidence to either unite or segregate Boesenbergia albomaculata and Curcumorpha longiflora in the same genus and demonstrate that more taxonomic data on the genus Boesenbergia and its relatives are needed before a final decision can be made. © 2011 Published by Elsevier GmbH. Introduction sification and the taxonomic status of various genera have been under investigation. With 57 genera and about 1300 species, the tropical mono- The molecular phylogenetic surveys (Kress et al., 2002) sug- cotyledonous family Zingiberaceae is the largest one of the eight gested the non-monophyly of Curcuma and Boesenbergia. But families in the order Zingiberales (Costaceae, Cannaceae, Heli- Ngamriabsakul and Techaprasan (2006) stated that Boesenbergia coniaceae, Lowiaceae, Marantaceae, Musaceae, Streliziaceae and is monophyletic, based on petA-psbJ spacer. It was also shown that Zingiberaceae). Members of Zingiberaceae are mostly distributed floral gross morphological characters, such as color of bractsand from India to New Guinea (Kress et al., 2002; Larsen et al., 1998). position of inflorescence, which are traditionally used in the tax- The most accepted classification of the Zingiberaceae includes four onomy of Curcuma and Boesenbergia, are highly homoplastic and tribes: Hedychieae, Alpinieae, Zingibereae and Globbeae (Burtt thus often unreliable for the definition of lineages (Ngamriabsakul and Smith, 1972; Holttum, 1950; Larsen et al., 1998; Schumann, and Techaprasan, 2006). Therefore, many relationships identified 1904; Smith, 1981; Takhtajan, 1997) based on vegetative and by morphology have not been found in accordance with molecular flowering features. However, Kress et al. (2002) have brought surveys. new sights into the evolutionary relationships and classification Moreover, chromosome numbers were not useful for delimi- of the Zingiberaceae based on molecular phylogenies. They pro- tation of major lineages, especially in Boesenbergia. Chromosome posed a new classification of the Zingiberaceae and recognized four numbers of Boesenbergia indicate that two different evolutionary subfamilies and four tribes: Siphonochiloideae (Siphonochileae), lines exist in the genus. One has the basic chromosome num- Tamijioideae (Tamijieae), Alpinioideae (Alpinieae, Riedelieae), and ber x = 10, while the other has x = 12. Confirmation of the two Zingiberoideae (Zingibereae, Globbeae). Takhtajan (2009) accepted different evolutionary lines and the monophyly of the genus Boe- Kress’ system in his update system of angiosperm classification. senbergia requires further studies (Eksomtramage et al., 2002; Since then, the congruence of morphological features with this clas- Ngamriabsakul and Techaprasan, 2006). Pollen characters have been used to assess systematic and phy- logenetic relationships in many taxonomic groups (Castro et al., 2009; Panajiotidis et al., 2000; Pardo et al., 2000). Pollen morphol- ∗ Corresponding author. Tel.: +86 20 3725 2565. ogy has been of particular significance in taxonomy and phylogeny E-mail address: [email protected] (N.-H. Xia). 0367-2530/$ – see front matter © 2011 Published by Elsevier GmbH. doi:10.1016/j.flora.2011.01.007 J. Chen, N.-H. Xia / Flora 206 (2011) 458–467 459 Table 1 Accessions of Curcuma and Boesenbergia with vouchers, habitat and source. Species Vouchers Habitat Source Curcuma aromatica Salisb.a J. Chen132 (IBSC) Sand soil along the road of Menghai, Yunnan, China FAA-fixed IBSC C. aromatica Salisb. J. Chen54 (IBSC) Sand soil along the road of Mengla, Yunnan, China FAA-fixed IBSC C. aromatica Salisb. J. Chen0812 (IBSC) Dry soil in Nanning, Guangxi, China FAA-fixed IBSC C. amarrisima Roscoe J. Chen144 (IBSC) Sand soil along the road of Menghai, Yunnan, China FAA-fixed IBSC C. elata Roxb J. Chen0813 (IBSC) Wet soil along the road at South China Botanical Living collection IBSC Garden, Guangzhou, China C. aff. elata Roxb.b J. Chen57 (IBSC) Margin of the forest of Xishuangbanna, Yunnan, FAA-fixed IBSC China C. flaviflora S. Q. Tong J. Chen0885 (IBSC) Margin of the forest of Menghai, Yunnan, China FAA-fixed IBSC C. kwangsiensis S. G. Lee & C. F. Liang J. Chen0816 (IBSC) Dry slope at South China Botanical Garden, Living collection IBSC Guangzhou, China C. aff. kwangsiensis S. G. Lee & C. F. Liang J. Chen0841 (IBSC) Sand soil along the road of Menghai, Yunnan, China FAA-fixed IBSC C. longa L. J. Chen0886 (IBSC) Sand soil along the road of Menghai, Yunnan, China FAA-fixed IBSC C. nankunshanensis X. B. Xu, J. Chen & J. Chen0815 (IBSC) In the pot at South China Botanical Garden, Living collection IBSC N. Liu Guangzhou, China C. phaecaulis Valeton J. Chen0828 (IBSC) Beside streams of Gulinqing, Yunnan, China FAA-fixed IBSC C. rubrobracteata Skorniˇ cková,ˇ M. Sabu J. Chen0843 (IBSC) Sand soil along the road of Menghai, Yunnan, China FAA-fixed IBSC & Prasanthkumar. C. sp. ‘pink flower’ J. Chen134 (IBSC) Sand soil along the road of Menghai, Yunnan, China FAA-fixed IBSC C. sichuanensis X. X. Chen J. Chen0850 (IBSC) Beside streams of Menghai, Yunnan, China Living collection IBSC C. wenyujin Y. H. Chen & C. Ling J. Chen0890 (IBSC) Beside the road at South China Botanical Garden, Living collection IBSC Guangzhou, China C. yunnanensis N. Liu & S. J. Chen J. Chen0883 (IBSC) Sand soil along the road of Menghai, Yunnan, China FAA-fixed IBSC C. zanthorrhiza Roxb. J. Chen58 (IBSC) Dry slope at XSBN Tropical Botany Garden FAA-fixed IBSC Boesenbergia albomaculata S. Q. Tong. J. Chen0834-1 (IBSC) Margin of the Forest at XSBN Tropical Botany FAA-fixed IBSC Garden, Yunnan, China B. longiflora (Wallich) Kuntze J. Chen169 (IBSC) Margin of the forest at South China Botanical Living collection IBSC Garden, Guangzhou, China a If three populations are given for one species, the upper one has been used for statistical analysis of quantitative characters measured under SEM and TEM in order to provide regular procedure in comparison between mean and standard deviations. b The specimens were determined with some doubts. of the family Zingiberaceae (Saensouk et al., 2009; Theilade et al., is provided in Table 1. When available, two or three collections 1993). Liang (1988) studied pollen morphology of Zingiberaceae were sampled for some species in order to be sure about the con- including Costaceae under LM and SEM. The results showed that stancy of pollen characters among different populations of one pollen grains of the Zingiberaceae are spherical, subspherical, ovoid species. Otherwise only one sample was prepared. Pollen obtained and prolate, respectively, 36–225 ␮m in size. The wall is composed mainly from blooming flowers was prepared for SEM, while pollen of a very thin exine and a thick intine. Based on the exine sculp- collected mostly from flower buds at start of anthesis was pre- turing, pollen grains of the Zingiberaceae/Costaceae lineage can pared for TEM observation. Most vouchers and all corresponding be divided into two types: inaperturate in the family Zingiber- microscope slides are deposited in the Herbarium of South China aceae and aperturate in the family Costaceae; and six subtypes: Botanical Garden, Chinese Academy of Sciences (IBSC). Herbarium psilate, spinate, cerebelloid-areolate, striate, verrucate, and fove- acronyms follow Index Herbariorum, 8th edition (Holmgren et al., olate. Liang (1988) emphasized that further palynological studies 1990). Taxonomic names are in accordance with the classifications concerning the phylogenetic placement of Boesenbergia and Cur- of Wu and Larsen (2000), the terminology follows Kress and Stone cumorpha are necessary. Mangaly and Nayar (1990) studied the (1982), Punt et al. (2007), and Hesse et al. (2009). palynology of South Indian Zingiberaceae, and divided the fam- For SEM observation of pollen morphology, pollen grains were ily Zingiberaceae into two groups (sulcate group and inaperturate collected from flowers and fixed in FAA in the field. The pollen group) according to the pollen morphology. Among them, the gen- grains were dispersed on stubs