Abstract: 1. History of development of the forest flora Since the Cenozoic period, the number of forest tree species has steadily risen. In the course of time, some of the archaic types slowly diminished and perished, and new forms gradually evolved. During the palaeocene, the numher of the gymnosperms (with the exception of conifers) and ferns drastically decreased, and that of conifers, on the contrary, increased significantly, and meantime the broad-leaved tree species also appeared. During the Neocene, the angiosperms expanded rapidly and the vegetation gradually shifted towards the mixed deciduous-evergreen forest. Shortly before the Quaternary, there was a series of world-wide climatic fluctuations, as illustrated by progress and retreat of glaciers, cold-resistant and warm-loving (thermophilic) plants appeared alternately. In the post-glaciation period, the zonal distribution of forest vegetation in Zhejiang Province was essentially similar to that of the present time. Excavations from Homu-tu, Yu-Yao County, reveal a luxuriant subtropical forest which existed 7000 years ago. 2. Characteristics of the flora and vegetation (1) Of ancient origin, with rich relic elements. Archaic gymnosperms such as Ginkgo biloba, Amentotaxus argotaenia, Pseudotaxus chienii, Torreya jackii, T. grandis, Taxus chinensis var. mairei, Podocarpus macrophyllus, P. neriifolia, etc, are all found in the Cretaceous deposits. The occurrence of Ginkgo can be traced hack to the Triassic. Most of the conifers, however, were found in the Jurassic, and they have remained to the present time as the main elements of the needleleaved forests. Among the primitive angiosperms, Magnoliaceae is represented by 19 species of 8 genera; Fagaceae and Lauraceae are the dominant evergreen broad-leaved tree species, the former by 6 genera and 43 species, and the latter by 10 genera and 42 species. Hamamelidaceae is represented by 10 genera and 18 species, while Ulmaceae, Tiliaceae, Elaeocarpaceae, by 21 species of 7 genera, 9 species of 2 genera and 6 species of 2 genera respectively. (2) Rich in species and consisting of diverse geographic elements, but dominated by the tropical ones. Throughout Zhejiang Province, there are over 1300 taxa of woody plants (including varieties and cultivated ones) belonging to 109 families and 423 genera. Among them, 8 families with 25 genera and about 45 species, are gymnosperms, and the rest, 101 families with 398 genera and about 1260 species and varieties, are angiosperms. The major angiospermous families include Mognoliaceae, Fagaceae, Lauraceae, Theaceae, Aquifoliaceae and Bambusoideae. Dominant families and genera are the tropical ones, and next in the order, are the East Asiatic, the E. Asia-N. American, then the temperate, the cosmopolitan, endemic and other elements. (3) Rich in endemic species, in monotypic and oligotypic genera. The endemic species include Abies beshanzuensis, Ostrya rehderiana, Carpinus putoensis, Carpinus tientaiensis, Celtis chekiangensis, Calycanthus chinensis, Machilus minutiloba, M. chekiangensis, Semiliquidambar caudata var. cuspidata, Acer aeutum, A. yangjuechi, A. Changhwaense, A. elegantulum, A. pauciflorum, Ilex qinyuanensis, Styrax zhejiangensis, Photinia zhejiangensis, Actinidia zhejiangensis, etc. The monotypic and oligotypic genera are examplified by Ginkgo, Pseudotaxus, Pseudolarix, Fokienia, Cyclocarya, Parakmeria, Pteroceltis, Sargentodoxa, Decaisnea, Aphananthe, Hemiptelea, Zelkova, Fortunearia, Semiliquidambar, Polithyrsis, Ostrya, Heptacodium, Tapiscia, Bretschneidera, Choerospondias, Kalopanax, Halesia, Hovenia, Emmenopterys, Eucommia, Pileostegia, Platycrater, Alniphyllum, etc. The majority of the species mentioned above are rare and precious ones. (4) Introduced species gaining importance Zhejiang Province is mainly situated in the mid-subtropical zone, and from Yukuan District and the Wenzhou Prefecture southwards it belongs to the evergreen broad-leaved south subtropical forest belt. A number of south subtropical species, such as Eucalyptus spp., Casuarina spp., Acacia mearnsii, have been successfully introduced into this region. The introduction of other species, such as Cinnamomum cassia, Grevillea robusta, Michelia alba, Canarium album, Litchi chinensis, Euphoria longan, Kandelia candel, are successful in certain areas. Small plantations of introduced species from S. W. China e.e. Cinnamomum glanduliferum, C. septentrionale have been established. In addition, Metasequoia glyptostroboides, Ulmus pumila, several exotic Pinus species, Carya illinoensis, Robinia pseudoacacia, Amorpha fruficosa, etc. are widely planted throughout Zhejiang Province. In recent years, cold-temperate species such as Chamaecyparis obtusa, Thuja standishii, Thuja occidentalis, Abies firma have been introduced and planted in the mountainous areas. The forest flora of the province is thus being further enriched. 3. Geographical analysis of the forest flora (1) The south part of Zhejiang lies in the transitional belt between the East and South China Floristic Regions, its east part being on the north margin of the South China Floristic Region, and its west part on the south margin of the East China Floristic Region. (2) The north part of the province is weakly influenced by the temperate elements, but the influence may extend to the central part of this province as the elevation there is higher. (3) Diverse floristic elements such as those belonging to Japan, Taiwan (China), C. China and S. W. China regions also occur in the province, especially in its western and eastern parts.

Key words: Forest flora, Zhejiang provice