Abstract: Yuanmou river valley is situated in the north-central part of Yunnan plateau. It is one of the most dry and hot river valley in Yunnan province. The vegetation of the valley is somewhat like the "savanna" of tropics. The flora below 1600 m of the valley has been studied in this paper. There are 78 families, 266 genera and 399 species appearing in the valley flora. Large number of tropical plantr, (specially the savanna elements are found in this area. The floristic com- position of the river valley and its relationship to the flora of neighboring district, the India savanna, have been discussed.

Key words: Flora

摘要： 元谋是我国著名的干热河谷之一。在元谋干热洒谷1600米以下的山坡上主要分布着稀树灌草丛植被。经研究计有种子植物78科、266属、399种，其中绝大部分草本和灌木种类。从种子植物的地理成分分析这里的区系成分带有明显的热带性质，其中出现在元谋的热带属占属总数（不包括世界分布属）的72．3％，温带分布属占26·4％，中国特有分布属占1．3％。这里的区系成分除了与其所处的滇中高原邻近地区关系很密切外，与印度等地的稀树草原也有联系，表现出了区系成分的古老联系和稀树草原植被的残余性。

关键词: 植物区系, 干热河谷, 稀树草原