Preliminary morphological assessment of six new, yellow flowering Camellia (Theaceae) species from Viet Nam

George [1]Orel Anthony S. Curry¹
Royal Botanic Gardens, Mrs Macquaries Road, Sydney, NSW 2000, Australia

1 Introduction

Historically only a relatively small number of Camellia species were considered to be native to the southern mountain regions of Vietnam. The northern parts of Vietnam (e.g. the Tam Dao National Park and the adjacent geographical areas which are relatively close to the Chinese border) were traditionally considered to be the major centres of distribution of Vietnamese Camellia species (Sealy, 1958; Chang & Bartholomew, 1984; Gao et al., 2005). Recent systematic exploration carried out by a team of Australian and Vietnamese scientists on the Da Lat Plateau and the Lang Biang Massiff in the southern provinces of Viet Nam resulted in the discovery of a number of new Camellia taxa, some of which have already been published (Orel, 2006; Orel & Wilson, 2010a, Orel & Wilson 2010b, Orel et al, 2012). These discoveries not only confirm the floral richness of this geographical area but also establish it as an important centre of Theaceae genetic diversity and the possible northern boundary of the hypothesized area of origin for genus Camellia (Orel & Marchant, 2006).

2 Materials and Methods

Morphological characters of 15 yellow flowering species of Camellia from Viet Nam and China were observed to indicate the interspecific status of the six newly discovered Camellia taxa from Viet Nam (Table 1.). All materials were collected in the wild and the exact provenance details for each were withheld for conservation reasons. General provenance and population data for all species used is presented in Table 1.

Table 1.  General provenance and population data for 15 yellow flowering Camellia species from Viet Nam and China that were used in this paper

*              Bold print denotes newly discovered Camellia species
**            Species in the process of publication, accession Nos. only

Morphological data was derived from observations of the six newly discovered Camellia species and the nine yellow flowering Camellia from Viet Nam and China. The flower colour and the dominant morphological traits of the six newly discovered species are presented in Table 2. Some 30 multiple state characters were scored from in situ observations. The assessments of herbarium materials were performed under laboratory conditions. The morphological matrix, where the absence of a character was denoted 0 and the presence of a character 1, 2, 3, 4, 5 and 6 was constructed and analyzed (Fig. 1.). Phylip 3.69, a computational program for inferring evolutionary phylogenies was used to generate the taxonomic trees.

Table 2.  Morphological details for six, newly discovered, yellow flowering Camellia species from Viet Nam

ITS (Internal Transcribed Spacer) molecular procedures were also used to attempt to resolve the taxonomic status of the six newly discovered Camellia species. Genomic DNA was extracted from the fresh leaves using a method similar to that of Dellaporta et al (1983, in Wilkie, 1997). ITS PCR amplification was achieved using a number of primer pairs, e.g. ITS4 and ITSleu1 (White et al 1990). Horizontal Agarose electrophoresis procedures followed the modified protocol of Sambrook et al (1989).

3 Results

The attempts to directly sequence the ITS PCR product of the six new Camellia species, without cloning, were not completely successful. Camellia dongnaiensis, C. inusitata and C. sp. 0720 provided marginally viable ITS PCR products. The ITS PCR products of the other three new Camellia species were judged to be inferior. As such the ITS molecular results were not included in this work.

4 Discussion

Historically only a relatively small number of yellow flowering Camellia species were considered native to the southern provinces of Viet Nam. The northern parts of Viet Nam, e.g. the Tam Dao National Park and its environs as well as the geographical areas relatively close to the Chinese border, were traditionally considered to be the major centres of yellow Camellia distribution. This fact can be amply demonstrated by even a cursory look at the pertinent literature. The total number of published, southern Vietnamese yellow flowering Camellia species fluctuates from author to author and is subject to issues surrounding the flower colour of herbarium specimens, e.g. of C. krempfii (Gagnep.) Sealy and C. dormoyana (Pierre ex Laness.), and inconsistencies present in published descriptors (C. gilbertii (A. Chev.) Sealy) (Sealy, 1958; Chang & Bartholomew, 1984; Ho, 1991; Tran, 2002; Gao et al., 2005).

The relatively recent exploration of the southern provinces of Viet Nam carried out by the Australian-Vietnamese scientific team resulted in the discovery of at least six new yellow flowering Camellia species (Orel, 2006; Orel & Wilson, 2010a, Orel & Wilson 2010b, Orel et al, 2012). These and numerous other Camellia and Theaceae finds established southern Viet Nam as an important centre of genetic diversity and the possible area of origin for genus Camellia (Orel & Marchant, 2006). The discovery of more than 30 new Camellia species (so far) in this region places the geographical area of southern Viet Nam on a par with other known global centres of diversity, e.g. the Western Ghat Mountains that hold about 30% of India’s plant species (Bawa & Krishnaswami, 2007) and the state of Georgia in the USA, which contains some 30% of all tree species of the USA and Canada (Brown & Kirkman, 1990).

It is important to note, that the six newly discovered Camellia species from south Viet Nam (Table 1.) possess a number of morphological characteristics that are quite dissimilar to those of the other, already described yellow Camellia taxa (Table 2.).  Some of these traits are not present in the morphologies of known yellow Camellia species. For example, to name only the most obvious dissimilarities, C. inusitata Orel, Curry & Luu lacks secondary branching, C. sp. 698 and C. luteocerata possess a spiral and not whorled petal arrangement and C. sp. CT5 has a large inflorescence composed of 12 to14 flower buds (Table 2.).

Figure 1. which shows the interspecific relationships that exist between the six newly discovered Camellia species and the nine yellow Camellia species from Viet Nam and China reflects the morphological differences that exist between the ‘new’ and the ‘old’ Camellia species. C. luteocerata Orel, C. sp. 698, C. sp. 0720 and C. sp. CT5 nest separately within the dendrogram (Fig. 1.). The position of

C. dongnaiensis Orel with the rest of the Vietnamese and Chinese yellow Camellia species is consistent with the published data (Orel, Marchant & Curry 2007) and that yet to be unpublished. C. dongnaiensis Orel seems to possess fewer primitive morphological traits than the geographically allied yellow Camellia species. The position of C. inusitata Orel, Curry & Luu is considered anomalous and the reasons for this are not precisely known. It appears that the reproductive characters of C. inusitata Orel, Curry & Luu, i.e. its floral parts, may be akin to other yellow Camellia species, but dissimilar to the other species’s vegetative characters. It is hoped that further morphological and molecular studies will more adequately explain this inconsistency. Data contained in Fig. 1. may have implications in regard to the general taxonomy of genus Camellia and also for the taxonomy of the family Theaceae.

The question: Do the rather unorthodox morphological dissimilarities of the six newly discovered species translate into a general genetic dissimilarity? This question can be answered in the affirmative. The phenotypic unorthodoxy is reflected in the respective Camellia genotypes. The attempts to directly sequence the ITS PCR product of the new Camellia species were only partially successful, even when using a number of previously tested, positive result bearing primers. As this paper is only a preliminary study into the interspecific relationships of the south Vietnamese yellow flowering species of Camellia, a larger study, that will eventually encompass all of the newly discovered Camellia species, is already in progress and will be published later.

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[1] Author for correspondence: honorary research associate; e-mail george.orel@rbgsyd.nsw.gov.au