甘肃洮河流域种子植物区系的初步研究

甘肃洮河流域地黄土高原和青藏高原的交汇地带，植物种类比较丰富，据初步统计，有种子植物１００科，４４８属，１３４６种，其种子植物区系具有下列基本特征；种类组成比较丰富，地理成分复杂，联系广泛，但以温带成分占绝对优势，具典型的北温带性质，区系成分过渡性强。根据特有种的分布情况和自然地理特征，洮河中上游植物区系应地横断山脉地区川西北，甘南，青东南地区，洮河下游应属于华北地区黄土高原亚地区。

A PRELIMINARY STUDY ON THE SPERMATOPHYTIC FLORA FROM TAOHE RIVER IN GANSU

The Taohe river in Gansu province is located in the confluent zone of Loess Plateau and Qinghai-Xizang plateau, where the seed plants are relatively abundant in species. According to preliminary statistics, the seed plants in this area comprise 1346 species (incl. ssp. and var.), 448 genera and 100 families. The primary characteristics of the spermatophyte flora from the Taohe river are: rich in species, complex in geographical elements, having an extensive connection with nearby floristic areas, but with temperate elements as absolute predominance, basically of N temperate in nature, and its floristic elements showing very obvious transition. On the basis of the distribution of endemic species and some physiographical features, the flora of middle-upper reaches of Taohe river belong to the subregion of NW Sichuan, S Gansu and SE Qinghai of Hengduan mountain, and the lower reaches of the river to the subregion of Loess Plateau of North China.