台灣新歸化菊科（Asteraceae）裸穗豬草

Ambrosia psilostachya DC. (Asteraceae) a Newly Naturalized Plant in Taiwan

This paper describes Ambrosia psilostachya DC. (Asteraceae) as a plant newly recorded to Taiwan. It has established its feral population in Kaohsiung County, and is closely related to exotic A. artemisiaefolia L. of Taiwan. However, the two species are distinguishable by the structure of their pinnatifid leaves. This paper also provides its distribution, living habitat, breeding (flowering and fruiting) period. 裸穗豬草（菊科）首次在高雄市左營區半屏山頂被採集，為台灣新歸化植物。本篇報告描述其形態特徵、地理分布及生育環境，並提供彩色圖片與繪圖，同時列製檢索表以區別裸穗豬草與同屬另一歸化植物豬草（A. artemisiaefolia L.）。