银合欢（学名：Leucaena leucocephala）别名白相思子、细叶番婆树、臭菁仔。为含羞草科银合欢属植物，原产墨西哥南部和中美洲北部，现扩散到世界各地热带和亚热带地区，名列世界百大外来入侵种。

银合欢由于树根会分泌出含羞草素抑制其他种植物生长，排他性极强又无天敌因而形成单一性的纯林地带，因此减低生物多样性、。幼叶及其荚果含丰富蛋白质，可做牛群饲料 ；但作为饲料时含羞草素在反刍动物瘤胃中所产生的代谢产物3-羟基-4-氧代吡啶基，对反刍家畜或人类都具有一定的毒性。

Leucaena leucocephala is a small, fast-growing mimosoid tree native to southern Mexico and northern Central America (Belize and Guatemala), but is now naturalized throughout the tropics. Common names include white leadtree, jumbay,river tamarind, Subabul, and white popinac. The specific name is derived from the Greek words λευκό, meaning "white", and κέφαλος, meaning "head", referring to its flowers. L. leucocephala is used for a variety of purposes, such as firewood, fiber and livestock fodder.