中国植物区系中的特有现象——特有属的研究

本文对我国种子植物特有属作了初步研究，提出如下几点粗浅的看法：     1．根据我国各特有属的现代地理分布格局，大部分特有属具有明显的温带性特点。     2．我国特有属在水平分布上具有极不均匀的特点。各特有属的广布程度都很低，生态特     化现象十分明显。在垂直分布上，则主要分布于中海拔地区。特有属数目并不随海拔增高而     增多。     3．根据特有属分布的密集程度和分布区边界的密集交叠情况，划定了三个特有属分布中    心，即川东—鄂西中心, 滇东南—桂西中心和川西—滇西北中心。前二中心可能是残遗中心，后一中心则可能为分化中心。

Endemism in the Flora of China—Studies on the Endemic Genera

China,  under highly varied ecological conditions resulted from wide lati- tudinal and altitudinal ranges and from the adequate precipitation,  has developed a very rich flora of great diversity. As far as flowering plants are concerned,  there are 2980 genera,  214 of which,  belonging to 64 families,  are endemic.  Among these ende- mic genera,  there are 9 genera of taxads and conifers, 19  genera of monocots  and others of dicots.  Of the approximately 129 herbaceous endemic genera in the Chinese flora as a whole,  about 22 (17%) are annual and 107 (83%) are biennial or perennial. In the present paper the ecological distribution,  the nature of endemic genera and the centers of endemism are discussed.      1.  Three types of endemic genera are distinguished,  neoendemics,  palaeoendemics and active epibiotics,  The endemic genera in the flora of China are,  for the most part, considered to be very old ones,  and most of them are of temperate nature.      2.  the degree of endemism in our 22 floristic regions is shown in Figure 1.  The areas richest in endemic genera in the Chinese flora as a whole are the 13,  16 and 17 regions.  The poorest are the 2,  4,  9 and 10 regions,  and no one in the 1 and 3 regions These results on floristic richness are of general applicability.      As shown in table 1,  the difference in the degree of endemism among the seven Chinese floristic subkingdoms are most pronounced.   101 endemic genera are known to occur in one subkingdom,  72 to occur in two subkingdoms,  and 3 to occur in four subkingdoms,  only one genus widely distributed in five subkingdoms.  However,  there is no genus occurring in seven subkingdoms. The difference in the degree of endemism in each subkingdom reveals that the distribution of endemic genera is not well-distri- buted in the Chinese flora as a whole.      Analysis of the vertical distribution of the 200 endemic genera of the Chinese flora bears out that there is no evident increase in endemism as a whole with altitude.      3.  Three centers of endemism are found (Fig. 2).  These are as follows:      a).  Eastern Sichuan-western Hubei center.      b).  Southeastern Yunnan-western Guangxi center.      c).  Western Sichuan-northwestern Yunnan center.  The degree of endemism andcharacters of endemic genera in each center are discussed.