Taxonomic Study of Camellia formosensis (Masamune et Suzuki) M. H. Su, C. F. Hsieh et C. H. Tsou (Theaceae)

The Taiwan native wild tea plant was first documented in 1717 on Chu-lo-hsien-chih. The utilization of this plant is mostly restricted to local people until 1999, when a black tea clone was bred by the Tea Research and Extension Station. The researches, applications and conservations on the Taiwan native wild tea plant were limited due to several uncertainty about its taxonomy. This dissertation is set out to elucidate the taxonomic status of the Taiwan native wild tea plant based on morphological and molecular evidences.

There are seven chapters in the dissertation. In chapter 1, the definition, background and taxonomic history of the Taiwan native wild tea plant were introduced.

Chapter 2 concerns about the Camellia buisanensis and the Taiwan native wild tea plant. Because of a lack of materials for examination, some taxonomists thought C. buisanensis is the same with the Taiwan native wild tea plant until living plants were rediscovered in January 2004. Differences between the two taxa become apparent. Morphological data indicate that C. buisanensis is indeed a member of the genus Pyrenaria. Therefore, C. buisanensis was treated as Pyrenaria buisanensis, the results were published in Taiwania (2004, 49: 201-208).

In Chapter 3, the relationship between the Taiwan native wild tea plant and its two closely related taxa - C. sinensis var. sinensis and C. sinensis var. assamica - was explored by numerical methods using morphological characters. Results of the cluster analysis and nonlinear principal component analysis supported the Taiwan native wild tea plant as a distinct taxon. Buds of the Taiwan native wild tea plant are glabrous or sparsely hairy, while those of C. sinensis var. sinensis and C. sinensis var. assamica are densely hairy. Ovaries of the Taiwan native wild tea plant are glabrous, while those of C. sinensis var. sinensis and C. sinensis var. assamica are densely hairy. Vegetative characteristics of the Taiwan native wild tea plant from Taitung are different from individuals in other area, suggesting differentiation or specialization in the Taitung population. The results had been accepted by Taiwania.

In Chapter 4, the morphology of pollens from the Taiwan native wild tea plant, C. sinensis var. sinensis and C. sinensis var. assamica were compared. The pollens of Taiwan native wild tea plant were different from the other two closely related taxa in the sculpture of nexine and the shape at the polar side. In contrast, C. sinensis var. sinensis and C. sinensis var. assamica couldn't be distinguished by the morphology of pollens.

In Chapter 5, the stomatal and leaf anatomy of the Taiwan native wild tea plant, C. sinensis var. sinensis and C. sinensis var. assamica were compared. As to the stomatal morphology, the Taiwan native wild tea plant except for the Nantou population didn't have the ribbed cuticles and heteromorphic stomata, while Nantou population, C. sinensis var. sinensis and C. sinensis var. assamica did. Therefore, stomatal morphology supported Nantou population is special. There was no markly difference in leaf anatomy. The density of stone cells in leaves of the Taiwan native wild tea plant seems to be higher than the other two taxa. However, future studies to quantify this character might provide further evidence on taxonomic properties.

In Chapter 6, phylogenetic analyses were conducted using sequences of two DNA fragments, RPB2 intron 11-16 and intron 23. Results by the maximum parsimony and neighbor joining supported the Taiwan native wild tea plant is monophyletic. The genetic distance between the Taiwan native wild tea plant and C. sinensis var. sinensis, or C. sinensis var. assamica, was larger than that between C. sinensis var. sinensis and C. sinensis var. assamica. Within the Taiwan native wild tea plant, Nantou and Taitung populations were similar than Chiayi-Pingtung population.

In Chapter 7, taxonomic treatment on the Taiwan native wild tea plant was proposed, according to results of the previous chapters. Because the Taiwan native wild tea plant is distinct from C. sinensis var. sinensis and C. sinensis var. assamica, a specific rank for the Taiwan native wild tea plant was proposed. The name was given as Camellia formosensis (Masamune et Suzuki) M. H. Su, C. F. Hsieh, et C. H. Tsou. Meanwhile, the Taitung population was named as C. formosensis var. yungkangensis M. H. Su, C. F. Hsieh, et C. H. Tsou, for its markedly differences in the vegetative morphology.