合欢树（学名：Albizia julibrissin），常简称为“合欢”，也叫“合昏”、“夜合”，主要是因为它的小叶一到夜晚就闭合到一起。此外还有“绒花树”、“鸟绒”、“马缨花”等名称。花瓣不显着，但雄蕊细长，下部白色上部粉红色，使花的形状类似一个挂在马颈下的红缨，因此得到这些名称。

合欢树原产于中国，性耐寒、耐热、耐干燥，生长迅速，枝条每年可以生长一米以上。初夏开花，花期较长，因此是非常好的行道树和园林绿化树，已经引种到北温带的很多各国。最早罗马人以为蚕丝制品产于这种树上，所以称其为“丝树”，至今西方许多种语言中将其称为丝树。合欢树木材结构较细，也可用于制造家具，但易开裂，需经过适当处理。

This page is about the tree described by Antonio Durazzini. John Gilbert Baker used the same scientific name to refer to Prain's Albizia kalkora, the Mimosa kalkora of William Roxburgh.

Albizia julibrissin (Persian silk tree, pink silk tree) is a species of tree in the family Fabaceae, native to southwestern and eastern Asia.

The genus is named after the Italian nobleman Filippo degli Albizzi, who introduced it to Europe in the mid-18th century, and it is sometimes incorrectly spelled Albizzia. The specific epithet julibrissin is a corruption of the Persian word gul-i abrisham (گل ابریشم) which means "silk flower" (from gul گل "flower" + abrisham ابریشم "silk").