臺灣新歸化植物──直立鴨跖草（鴨跖草科）

Commelina erecta L. (Commelinaceae), a newly naturalized species in Taiwan

本文報導臺灣鴨跖草科的新歸化種－直立鴨跖草（Commelina erecta L.）。此物種原產於美洲，在臺灣已分布全島低海拔道路邊或公園。本種與臺灣原生種耳葉鴨跖草的差異在於直立鴨跖草通常直立生長，側花瓣較大，約1.5cm；耳葉鴨跖草通常匍匐或橫臥生長，側花瓣較小，約1cm。本文提供此物種特徵描述和彩色照片，以增加臺灣的物種清單與鑑定之用。

This paper is a report of Commelina erecta L. (Commelinaceae), a plant species native to America, that is newly naturalized in Taiwan. It is found along roadsides and in parks at low altitudes in Taiwan. Commelina erecta can be distinguished from the endemic species Commelina auriculata by the stem habit and petal size in that the former has erect growth and lateral petals larger than 1.5 cm, while the latter is repent or procumbent and has lateral petals smaller than 1 cm. The description and photographs of this species are provided to add to the inventory of Taiwanese flora and for its identification.