Psalms 137:2 - Ellicott's Commentary On The Whole Bible

Willows. — It is perhaps not necessary to attempt to identify the trees mentioned in this verse, since the touching picture may only be a poetical way of expressing the silence during the exile of all the religious and festal songs. The ‘ereb’ is certainly not the willow, a tree not found in Babylonia, but the poplar (Populus Euphraticus).