Willows, Poplars, Aspens

According to the translation of Psalm 137 preferred by the U.S. Conference of Catholic Bishops, the Jews in Babylonian exile hung up the harps on aspens. This surprised me. The Septuagint, the Vulgate, and King James Version all say that it was on willows. The Jerusalem Bible says poplars; the Revised Standard Version says willows but footnotes that with "or poplars".

The National Audubon society says that willows and poplars are two genera of the willow family. The American aspens are in the genera Populus (Latin for poplar). In the notes to his edition of The Odyssey, W.B. Stanford says of Book VIII, line 106

'Like the leaves of a tall poplar-tree': the comparison is between the continuous motion of the lightly hung leaves (probably of the aspen, Populus tremula) and the busy hands of the women [busy at weaving and spinning]....

So there is warrant for taking what are called poplars to be aspens. But then The Odyssey's word is αἴγειρος, poplar, and the Septuagint's is ἰτέα, willow.

 I suppose that my surprise on Sunday derived from the supposition that the aspen is a tree of the mountains. My first recollection of them is on the foothills of the Rocky Mountains, a much cooler and drier area than Babylonia.  And all aspens do seem to prefer cooler climates.