关键词: 紊蒿属, 新种, 分类, 演化

Abstract: A new species-Elachanthemum polycephalum Z. Y. Zhu et C. Z. Liang, -is de-scribed in detail and the problem of the classification position of Elachanthemum is discussed by mor-phological characteristics, ecological properties, geographical distribution, and flora origin. Morpho-logically, although Elachanthemum is similar to Stilpnolepis, there are obvious differences on the mor-ph and structure of flowers, achenes and pollen grains between two genera. Therefore, the Elachanthemum is an independent genus and can not be merged into Stilpnolepis. The genus is a primitive genus in the category of Artemisia, and it, perhaps, come from the Pro-Artemisia that distributed in the northem part of Asia in tertiary. It is a relict xerophytic element in the eastern part of Tethys, and is an endemic genus in the desert of Asia Media (Gobi desert). The discovery of the new species in Elachanthemum manifest that the species differentiation are stili progressing in desert flora, and make the Elachanthemum from a monospecific genus to olig-specific one (2 species).

Key words: Elachanthemum, new species, classification, evolution