桦木科植物的系统发育和地理分布(待续)

本文对桦木种植物的研究历史作了详细的总结。在钻研文献的基础上，补充了部分系统学资料，使得花序、花，花粉、叶表皮等各类性状能够在属间进行比较。根据外类群比较、和谐性分析等原则确定了性状的演化极性，利用最大同步法和最小平行演化法对桦木科植物进行了分支分析。对各属的现代分布和地史分布作了描述，在此基础上，讨论了桦木科植物的分布中心、起源地、起源的时间和散布的途径。作者试图回到遥远的晚白垩纪和早第三纪，从描绘桦木科植物起源和早期分化的古地理和古气候背景人手，分析了在这种背景下桦木科植物所发生的空间辐射以及植物体本身所产生的形态进化，以求得对桦木科植物起源、散布和分化作出比较合理的解释。最后对桦木科组以上的等级作了分类处理。

Phylogeny and Phytogeography of the Betulaceae (to be continued)

 In the present thesis, a detailed review of the literature was given on the Betulaceae. Some new data was provided based on the author’s studies in order to analyze various characters,  such as inflorescence,  flower,  pollen and leaf epidermis,  among the genera treated. The polarity of the characters was determined according to the criteria of outgroup comparison and compatibility analysis. A cladistic analysis was made using the methods of Maximal Same Steps and Minimal Parallel Evolution developed by Xu (1993). The generic distributions in both modern and fossil times were outlined, and their distribution center, place and time of origin and the way of dispersal were discussed. An attempt was made to discuss early differentiation, geographical radiation and morphological evolution of the family on the background of paleogeography and paleoclimatology, tracing back as far as the Late Cretaceous and Early Tertiary. Finally, supraspecific taxa, from section to tribe, were systematically arranged.