TAXONOMY

TAXONOMY
TAXONOMY BIOGRAPHY
TAXONOMY CAMUS
TAXONOMY NIXON
TAXONOMY SCHWARZ
TAXONOMY ZHENG

Depending on the authors there are between 300 (Lawrence, 1951; Elias, 1971) and 600 (Soepadmo, 1972) reported oak species. Since the beginning of the linnean taxonomy, the classification within the genus Quercus has raised conflicting opinions, from De Candolle (1868) to Nixon (1993), and more then 20 classifications were proposed. Disagreements are due either to the characters to be used for the classification, the infrageneric subdivisions adopted (sub genus or sections), and species delineation. There is so much variation within species that the concept of species has been questioned by several authors (Burger, 1975 ; Van Valen, 1976) and further complications in taxonomy are due to frequent interspecific hybridisation.

Because of its immense size and wide distribution, the authors did not always agree among them, neither for the classification nor about the criteria to be used. In addition, classifications are often limited to a restricted part of the distribution of the genus that constitutes an additional heterogeneity factor. The most complete classification, as much for its geographic as specific cover, is that of Camus (1936-1954). Classifications criteria used by Camus are mostly based on foliar and fruit characteristics. In Camus’ classification the genus Quercus (sensu lato) is subdivided in two sub genera: sub genus Euquercus (Quercus sensu stricto) and sub genus Cyclobalanopsis. There are about 150 species belonging to Cyclobalanopsis which exist  only in South Asia, whereas species belonging to Euquercus are the more familiar oak species. The sub genus Euquercus (Quercus sensu stricto) has been further subdivided into 6 different sections by Camus (1936-1954).

Earlier taxonomists have suggested that the genus Quercus is heterogeneous enough that it should be divided into two or more genera. Schottky (1912), Trelease (1924) Hjelmqvist (1948), Brett (1964), Liu and Liao (1976). Schwarz (1936, 1964) even divided Quercus into four separate genera. Others, in contrast, have suggested that Quercus should be united to the genus Lithocarpus (De Candolle 1868 ; Bentham & Hooker, 1880 ; Corner, 1939).

In comparison to Camus’ classification, the section Cerris (sensu Camus) was divided into additional sections by Asian botanists particularly (2 sections, section Brachylepides and Aegilops, Zheng, 1985, for example). This author also introduced a new section Englerianae merging species that belonged to sections Lepidobalanus and Cerris (sensu Camus). In the same way, Schwarz (1964) equally proposed to individualize the subsection Cocciferae of section Cerris (sensu Camus) with the species Q. ilex into section Sclerophyllodrys.

References

Bentham G. & Hooker J. D. 1880. Genera plantarum, Volume 3, Part 1. L. Reeve & Co., London.

Brett D. W. 1964. The inflorescence if Fagus and Castanea, and the evolution of the cupules of the Fagaceae. New Phytol. 63: 96-118

Burger W. C. 1975. The species concept in Quercus. Taxon 24: 45-50

Camus A. 1936-1954. Les chênes, Monographie du genre Quercus et Monographie du genre Lithocarpus. Encyclopédie Economique de Sylviculture. Vol. VI, VII, VIII. Editions Lechevalier (Paris)

Corner E. J. 1939. Notes on the systematy and distribution of Malayan phanerogams. Gard. Bull. Straits Settlem 10: 239-329

De Candolle 1868. Prodromus systematics naturalis regni vegetabilis. Cupuliferae, Part 16 (2). Victoris Masson & Filii, Paris.

Elias T. S. 1971. The genera of Fagaceae in the southeastern United States. J. Arnold Arbor. 52: 159-195

Hjelmqvist H. 1948. Studies on the floral morphology and phylogeny of the Amentiferae. Bot. Not. Suppl. 2: 1-171

Lawrence G. H. M. 1951. Taxonomy of Vascular Plants. MacMillan Co., New York

Liu T. S., Liao J. C. 1976. Fagaceae. In H-L. Li et al. [eds.], Flora of Taiwan, Vol. 2, pp. 49-104

Nixon K. C. 1993 Infrageneric classification of Quercus (Fagaceae) and typification of sectional names. Ann. Sci. For. 50, Suppl. 1: 25s-34s

Soepadmo E. 1972. Fagaceae. Flora Malenesia. Ser. I. 7: 265-403

Schottky E. 1912. Die Erichen des extratropischen Ostasiens und ihre pflanzengeographische Bedeutung. Bot. Jahrb. Syst. 47: 617-708

Schwarz O. 1936. Entwurf zu einen natürlichen System der Cupuliferen und der Gattung Quercus L. Notizbl. Bot. Gart. Berlin-Dahlem 8: 1-22

Schwarz O. 1964. Quercus L. In: Tutin, T. G., Heywood, V. H., Burges, N. A., Valentine, D. H., Walters, S. M. and Webb, D. A. (eds) Flora Europaea, vol. 1: Lycopodiaceae to Platanaceae, pp. 61-64. Cambridge University Press, Cambridge

Trelease  W. 1924. The American oaks. Mem. Natl. Acad. Sci. 20: 1-255

Van Valen L. 1976. Ecological species, multispecies, and oaks. Taxon 25: 233-239

Zheng, W. J. Editor in Chief. 1985. Chinese Arboretum, Volume 2, Chinese Forestry press, Beijing. 2198-2357 (in Chinese)