THE CHARACTERISTICS OF HUNAN FLORA
Qi Cheng-jin
1984, 4(1):
130-145.
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Geologically Hunan province belongs to a part of SouthChina which has not been covered by the sea since the TriassicPeriod. As the sea receded a variety of land plants such as Bennettitales, Cycadales, Ginkgoales etc. began to appear. Therecent conifers and angiosperms originated and developed inthe Jurassic and Cretaceous periods. By the end of the Ter-tiary Perioe, the majority of Hunan flora had been established and were taxonomically similar to the recent flora; they seemed to have suffered no severy damage from the subsequent Quaternary ice. Thus, the genera and species number in Hunan are plentiful and complex, and a great number of relic, ancient, and primitive species have been conserved. Flowering plants and ferns in Hunan include about 244 families, 1089 genera (1200 genera including cultivated plants) and 4005 species, which represent 16% of China's plant species. Of these, more than 1900 species are woody plants, making up 25.3% of all woody species in China. Although many families are represented in Hunan, a high concentration of genera and species occurs in the following families: Taxaceae, Cephalotaxaceae, Taxodiaceae, Fagaceac, Lauraceae, Magnoliaceae, Theaceae, Hamamelidaceae, Flou-cortiaceae, Elaeocarpaceae, Styracaceae, Alangiaceae, Hydran-geaceae, Nyssaceae, Aceraceae, Aquifoiaceae, Corylaceae, Juglandaceac, Ulmaceae, Lardizabalaceae, etc. These families comprise the fundamental floral composition of Hunan province. Geographical elements (based on geographic distribution)are complex and varied; they may be divided into 13 types of regional distributions. The statistical data and results of these classifications are shown in this paper. Based upon our statistics and analysis, some fundamental characterisites of Hunan flora can be summarized as follows. 1) Floristic elements are complex and varied, originating from varied geographical elements (regional distributions). There are 13 geographical elements and these may be separated into three climatic types; the tropical distribution (481genera, 47.9% of total); the subtropical distribution (225 genera, 22.3% of total); and the temperate distribution (297genera, 29.7% of total). 2) The geomorphological transitions within Hunan province which occur from east to west and from south to north inChina are accompanied by transitional and convergent features of different floristic elements, especially between flora of EastChina and Central China, as well as between the flora of bothNorth and South China. 3) As stated above, the richness in relic and ancient types, as well as in monotypic and oligotypic types show that the floristic origin is ancient, perhaps representing Tertiary flora on the whole. 4) The flora are rich in endemic species of Asia, China, and East Asia-North America. These three compositions include 280 genera, making up 28% of the total flora of Hunan, and represent Ginkgo, Metasequoia, Cathaya, Eucommia, Bretschneidera, Davidia, etc. which are essential components of east asian flora. The relations of Hunan flora to the neighboring areas are described and discussed in this paper.
