本文之目的在探討帝國日本熱帶植物知識的形成，以林業學者金平亮三（1882-1948）為例，檢視其如何在跨國脈絡下建立起熱帶植物地理的科學概念。金平亮三熱帶植物地理概念的建立深受不同網絡影響，其中又以他與美國植物學家Elmer Drew Merrill連結的關係最值得注意。金平曾長期任職於臺灣總督府的林業（試驗）機關（1909-1928），嗣後轉至九州帝國大學農學部執教鞭；Merrill則在二十世紀初於美屬菲律賓植物調查和研究機關擔當要職，1920年代中期後再回到美國本土接掌紐約植物園和哈佛阿諾德樹木園等單位。透過兩人在臺灣、菲律賓和東南亞等地植物採集與標本鑑識工作的相互支援，部分植物地理的議題進一步得到釐清。尤其是華萊士線北段的修正，更能說明臺灣和菲律賓之間植物物種的親緣關係。藉由熱帶植物知識發展的探討，本文認為：金平亮三的學術成就並非在蒐集最多的熱帶植物標本，而是有系統地組織前人獲取的植物知識，並達到初步描繪其所謂南洋植物相（flora of Micronesia）的成就。更重要的是：1900年代起，Merrill及其同僚以菲律賓群島、關島和鄰近島嶼為研究場域，戮力收集標本、文獻所建構的熱帶植物知識，是金平整個熱帶植物誌概念建立高度倚賴的第二手資料。

The article aims to explore the network that formed the Japanese tropical botanical knowledge by examining Kanehira Ryozo (1882-1948)'s role in circulating the ideas of tropical phytogeography. In this article, the author suggests that the establishment of flora knowledge usually requires collective work with comprehensive botanical survey and adequate determination. The materials the author used to study this topic consist of official documents and the academic works of Kanehira Ryozo. With these materials, he was able to trace the field work of Kanehira during 1909-1928 in Japanese Taiwan and the Japanese Mandate in Southeast Asia. The American botanist, Elmer Drew Merrill (1876-1956), was an important collaborator in establishing knowledge of tropical flora by Kanehira Ryozo. In short, the contribution Kanehira made in the formation of knowledge on tropical flora was to integrate distributed ideas systematically rather than hunt for as many plant specimens as possible.