The position of the genus Camellia L. (Theaceae) in some classification systems

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Far Eastern Federal University

The position of the genus Camellia L. (Theaceae) in some classification systems

Quach Van Hoi, R.V. Doudkin, Nguyen Tuan Khoi

Abstract

The genus Camellia was first established by Linnaeus in “Species Plantarum”. It is a genus of flowering plants in the family Theaceae. More than 400 species have been named and published, but the number has been reduced to between 80 and 280 species by combination during taxonomic revisions. Distribution of this species ranges from Bhutan, Northeastern India, China, Japan, to Southeast Asia. Many studies have been conducted to classify the genus Camellia based on morphological characteristics or molecular biological techniques. Through studies, it is shown that the morphological characteristics of fruits, flowers, and leaves are still important for the classification and arrangement of the Camellia genus in the classification system. Over different periods, the genus Camellia was classified into different positions in the classification systems. Some research on taxonomic systems of the Theaceae family determined the position of the genus Camellia. Although the genus Camellia can be categorized into different sub-families, tribes, or sub-tribes, the genus name Camellia has remained. The position of the genus Camellia belongs to the Theaceae family.

Keywords: Camellia, classification system, Theaceae, taxonomy, morphological characteristics

Положение рода Camellia L. (Theaceae) в некоторых классификационных системах

Quach Van Hoi, R.V. Doudkin, Nguyen Tuan Khoi

Дальневосточный федеральный университет, Владивосток, Россия

Camellia L. is the largest genus in the Theaceae family [1-4]. The first understanding of the Camellia was a tea tree. In addition to being used as a beverage, the Camellia was served widely in China as a kind of herb that significantly benefited human health. Linnaeus reported this species in “Species Plantarum” with the name Thea sinensis, then renamed Camellia sinensis [5]. He further documented the Camellia japonica, an ornamental plant grown in Japan. Additionally, the author established two genera Thea and Camellia: Thea sinensis belonged to the genus Thea (Class Polyandria Monogynia) and Camellia japonica belonged to the genus Camellia (Class Monadelphia Polyandria). That the Camellia genus was first established by Linnaeus in “Species Plantarum” is considered the foundation for studying the classification of Camellia later [5].

Seemann is the last author who remained Thea and Camellia names as two distinguished genera [6]. After Seemann, two genera Thea and Camellia were merged into a consistent name, Camellia. Many studies have been conducted to classify the genus Camellia based on morphological characteristics [1, 3, 7-10] or molecular biological techniques [11]. Over different periods, the genus Camellia was classified into different positions in the classification systems. Some taxonomic systems of the Theaceae were reviewed for an overview of the position of the genus Camellia.

Materials and methods

Some taxonomy systems of the Theaceae family and documents related to the genus Camellia have been studied to determine the position of the genus Camellia in the taxonomic system. The main systems studied include the morphological classification system of Airy-Shaw [7], Sealy [10], Keng [9], Chang [1, 8], and Ming & Bartholomew [3], and molecular biology techniques of Prince & Parks [11].

Results and discussion

The classification system of Airy-Shaw (1936)

Airy-Shaw's system divides the family Theaceae into two tribes, Camellieae and Gordonieae. The tribe Camellieae includes the subtribe Camelliinae (Camellia,

Tutcheria, Piquetia, and Stereocarpus) and the subtribe Laptaceinae (Laplacea, Polyspora, and Pyrenaria). The tribe Gordonieae includes the subtribe Gordiniinac (Gordonia, Franklinia, and Schima) and the subtribe Stewartiinae (Stewartia) (Table 1).

The study of Airy-Shaw is based on flower and fruit characteristics [7]. In the Theaceae family, Airy-Shaw characterized the tribe Camellieae as a pedicel with many bracteated leaves, petals and sepals randomly arranged in a spiral fashion, and a fruit capsule with a persistent columella [7]. He further divided the tribe Camellieae into two sub-tribes Camelliinae and Laplaceinae based on the difference between wingless seeds and winged seeds or drupaceous berries. He then divided the Camelliinae sub-tribe into several genera, including Camellia. To conclude, according to this classification system, the Camellia genus belongs to the sub-tribe Camelliinae, the tribe Camellieae of the Theaceae family.

classification genus camellia morphological

The classification system of Sealy (1958)

Sealy's system classified the family Theaceae into one tribe Gordonieae including the sub-tribe Camelliinae (Camellia, Pyrenaria, Yunnanea, and Tutcheria), the sub-tribe Gordiniinac (Gordonia, Laplacea), and the sub-tribe Schiminae (Schima, Hartia, and Franklinia) (Table 1).

The classification system of Sealy was strongly influenced by the fruit dehiscence, the gross morphology, as well as seed characteristics such as the presence or absence of petals and the amount of endosperm [10]. In the tribal classification systems, Sealy's explanatory text is limited or entirely lacking treatments. As a conclusion, the Camellia genus belongs to the sub-tribe Camelliinae and the tribe Gor- donieae of the Theaceae family.

The classification system of Keng (1962)

Keng's system divides the family Theaceae into two tribes, Camellieae and Gordonieae. The tribe Camellieae includes the sub-tribe Camelliinae (Camellia, Stereocarpus, Piquetia, and Yunnanea) and the sub-tribe Pyrenariinae (Pyrenaria and Tutcheria). The tribe Gordonieae includes the sub-tribe Gordiniinac (Gordonia and Laplacea), the sub-tribe Schiminae (Schima and Franklinia), and the subtribe Stuartieae (Hartia and Stuartia) (Table 1).

Keng concurred with Sealy's classification system in the use of fruit and seed characteristics for classification [9]. However, he stated that the classification would be better if more fruits and seeds' characteristics were used. Despite reusing the morphological characteristics of Sealy (1958), he examined more detailed characteristics such as whether the endosperm is copious or scanty and whether the columella center lacked or absence. Besides, he added anatomical characteristics such as the sclereid distribution in the leaves. Keng categorized the fruit with a persistent central columella, seeds having a thin endosperm, and a large embryo into the tribe Gordonieae. Characteristics such as central columella, unwinged seeds without endosperm, and large embryo referred to the tribe Camellieae. According to the classification of Keng, the Theaceae family consists of two tribes in which the tribe Camellieae is divided into two sub-tribes Camelliinae and Pyrenariinae. Also, the sub-tribe Camelliinae is subdivided into four genera, including the Camellia genus. To sum up, in the system of Keng (1962), the genus Camellia belongs to the sub-tribe Camelliiae and the tribe Gordonieae of the family Theaceae.

The position of the genus Camellia in the classification systems (CAPITAL letters are sub-family or tribe, underlines are sub-tribes, italics are genus)

The classification system of Chang (1984, 1998)

Chang's system divides the family Theaceae into four tribes Theeae (Camellia and Tutcheria), Gordonieae (Gordonia, Schima, and Apterosperma), Stewar- tieae (Hartia and Stewartia), and Pyrenarieae (Pyrenaria and Parapyrenaria) (Table 1).

In Chang's system (1984, 1998), the explanatory text is limited or entirely lacking treatments [1, 8]. This system divided the Theaceae family into tribes but did not divide them into sub-tribes. Moreover, he did not use the name Camellieae to replace the name Theeae. In Chang's system, the genus Camellia belongs to the tribe Theeae of the Theaceae family.

The classification system of Prince & Parks (2001)

Prince & Parks' system divides the family Theaceae into three tribes Theeae (Camellia, Polyspora, Pyrenaria, Laplacea, and Apterosperma), Gordonieae (Franklinia, Gordonia, and Schima), and Stewartieae (Stewartia) (Table 1).

Prince & Parks (2001) based on molecular biology techniques to classify the Theaceae family [11]. This classification system remained three tribes Theeae, Gordonieae, and Stewartieae; simultaneously, erased the tribe Pyrenarieae from Chang's system (1998). In their system, the tribe Theeae has the largest number of genera (five genera), including the Camellia genus. All things considered, in this system, the position of the genus Camellia is similar to in the system of Chang (1998), relating to the tribe Theeae of the Theaceae family.

The classification system of Ming & Bartholomew (2007)

Ming & Bartholomew' system divides the family Theaceae into two subfamilies Theoideae (Camellia, Pyrenaria, Polyspora, Apterosperma, Schima, and Stewartia) and Ternstroemioideae (Ternstroemia, Anneslea, Eurya, Euryodendron, Adinandra, and Cleyera) (Table 1).

The classification system of Ming & Bartholomew (2007) is based on characteristics of bisexual or unisexual flowers, characteristics of stamens, capsular or baccate fruits, dehiscent, drupaceous, or indehiscent fruits to classify the Theaceae family into two sub-families Theoideae and Ternstroemioideae [3]. The sub-family Theoideae is divided into six genera, including the genus Camellia. The genus Camellia is distinguished from other genera by its large fruit size, wingless seeds, and dehiscent capsule from the apex. By and large, according to Ming & Bartholomew' system (2007), the genus Camellia belongs to the sub-family Theoideae of the Theaceae family.

Conclusion

Through studies, it is shown that the morphological characteristics of fruits, flowers, and leaves are still important for the classification and arrangement of the Camellia genus in the classification system. The main features for identifying this genus are: Shrubs or small trees, rarely large trees or evergreens; petiolate or rarely sessile and amplexicaul leaves; narrowly elliptic, elliptic, oblong-elliptic, oblong, obovate, oval, and glabrous leaf blade; acuminate, acute or obtuse leaf apex; acute, obtuse or nearly rounded leaf base; serrate, serrulate, or rarely entire margin; pedicellate or sessile flowers; bracteoles differentiated or not differentiated from sepals;

numerous stamens; capsule fruit, rarely drupe; elliptic, flattened-globose, globose, ovoid, obovoid, 3-5-loculed, sometimes reduced to 1- or 2-loculed shape; persistent columella; globose, semi-globose, or polygonal seeds; full and fleshy with high oil content cotyledons; absent endosperm.

Through research into the classification systems of the plant taxonomists, it can be stated that there are many views and many classifications of the family Theaceae. Although the genus Camellia can be classified into different sub-families, tribes, or sub-tribes, the genus name Camellia has remained. The position of genus Camellia belongs to the Theaceae family.

References

1. Chang H. T., Bartholomew B. Camellias. London: B. T. Bastford Ltd., 1984. 211 p.

2. Ho P. H. Theaceae // Cay co Viet Nam [An illustrated flora of Vietnam]. Ho Chi Minh City: Youth Publishing House, 1999. Vol. 1. P. 424-432.

3. Ming T. L., Bartholomew B. Theaceae // Flora of China. Vol. 12. Hippocastanaceae through Theaceae / eds.: Z.-Y. Wu, P. H. Raven, D. Y. Hong. St. Louis: Science Press: Beijing and Missouri Botanical Garden Press, 2007. P. 366-478.

4. Orel G., Curry A. S. In pursuit of hidden Camellias; or 32 new Camellia species from Vietnam and China // Theaceae Exploration Associates. Sydney, Australia, 2015. 339 p.

5. Linnaeus C. Camellia // Species Plantarum II. 1753. 698 p.

6. Seemann B. Synopsis of the Genera Camellia and Thea // Transactions of the Linnean Society of London. 1859. Vol. 22, № 4. P. 337-352.

7. Airy-Shaw H. K. Notes on the genus Schima and on the classification of the Theaceae - Camellioideae // Bulletin of Miscellaneous Information (Royal Botanic Gardens, Kew). 1936. Vol. 1936. P. 496-499.

8. Chang H. T. Theaceae // Flora Republ. Pop. Sin. / ed. Z. Y. Wu. N. Y.: Science Press, 1998. Vol. 49. P. 195-251.

9. Keng H. Comparative morphological studies in Theaceae // Univ. Calif. Publ. Bot. 1962. Vol. 33. P. 269-384.

10. Sealy J. R. A revision of the genus Camellia // Royal Horticultural Society. London, 1958. 239 p.

11. Prince L. M., Parks C. Phylogenetic relationships of Theaceae inferred from chloroplast DNA sequence data // Am. J. Bot. 2001. Vol. 88. P. 2309-2320.

References

1. Chang H.T., Bartholomew B. Camellias. London: B. T. Bastford Ltd., 1984:211.

2. Ho P.H. Theaceae. Cay co Viet Nam [An illustrated flora of Vietnam]. Ho Chi Minh City: Youth Publishing House, 1999;1:424-432.

3. Ming T.L., Bartholomew B. Theaceae. Flora of China. Vol. 12. Hippocastanaceae through Theaceae. Science Press: Beijing and Missouri Botanical Garden Press, 2007:366-478.

4. Orel G., Curry A.S. In pursuit of hidden Camellias; or 32 new Camellia species from Vietnam and China. Theaceae Exploration Associates. Sydney, Australia, 2015:339.

5. Linnaeus C. Camellia. Species Plantarum II. 1753:698.

6. Seemann B. Synopsis of the Genera Camellia and Thea. Transactions of the Linnean Society of London. 1859;22(4):337-352.

7. Airy-Shaw H.K. Notes on the genus Schima and on the classification of the Theaceae - Camellioideae. Bulletin of Miscellaneous Information (Royal Botanic Gardens, Kew). 1936;1936:496-499.

8. Chang H.T. Theaceae. Flora Republ. Pop. Sin. N. Y.: Science Press, 1998;49:195-251.

9. Keng H. Comparative morphological studies in Theaceae. Univ. Calif. Publ. Bot. 1962;33:269-384.

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