台灣新歸化禾本科植物──彎穗草

Dinebra retroflexa (Vahl) Panz.—A newly naturalized Poaceae in Taiwan

禾本科（Poaceae）彎穗草（Dinebra retrofiexa (Vahl) Panz.）原產舊大陸熱帶地區，包括非洲和亞洲的熱帶乾燥開闊地。本種為一年生草本，花序由小穗組成，呈狹長橢圓形，長6-25cm，成熟時常下彎倒伏；每節具2-4個短總狀花序；小穗無柄呈兩列排列，基部具關節成熟易掉落；穎片細長成針狀，比被包覆的小花長等特徵，能與台灣已知的種類區別。本文報導彎穗草歸化於台灣北部和南部低海拔地區的農田和道路邊緣，描述其外部形態特徵、彩色照片和生態特性。

Dinebra retroflexa (Vahl) Panz., belonging to the grass family, is native to the tropics of the Old World, including the tropical dry open lands of Africa and Asia. This small herb can be distinguished by its terminal 6-25 cm long inflorescence, two to four racemes arranged spikelets on main axis, spikelets with joints that fall off easily, and longer glumes than the flowers. In this paper, we report the naturalization of Dinebra retroflexa in low-altitude farmland and road edges in northern and southern Taiwan, and describe its morphological characteristics, color photo, and ecological characteristics.