Alnus nepalensis D. Don (Betulaceae), a Newly Naturalized Tree in Taiwan

臺灣新歸化樺木科植物－－尼泊爾赤楊

We document the naturalization of Alnus nepalensis D. Don (Betulaceae), native to southern Himalaya from Pakistan to southwest China, has been found at middle altitude in central Taiwan. A taxonomic treatment, line drawings, color photographs, and distributions are provided to aid in identifi cation of this alien tree. A detailed comparison table between A. nepalenssi D. Don and A. formosana (Burkill ex Forbes & Hemsl.) Makino are also provided. 本文首次報導原產亞洲喜馬拉雅山脈南部及中國大陸西南部的尼泊爾赤楊（Alnus nepalensis D. Don），目前已歸化於台灣中部南投中海拔山區。本文描述其形態特徵、地理分布及生育地環境，並提供彩色圖片與線繪圖以資辨識。本種與台灣原生種台灣赤楊（A. formosana(Burkill ex Forbes & Hemsl.) Makino）近似，但與後者主要的區別在於前者具大型葉片、8-16對側脈及圓錐花序。近年來進行調查時，發現其野外族群穩定成長、更新良好。