Easton's Bible Dictionary: M. G. Easton, M.A., D.D.
Referred to only in Dt. 32:32. Among the many conjectures as to this tree, the most probable is that it is the 'osher of the Arabs, which abounds in the region of the Dead Sea. Its fruit are the so-called "apples of Sodom," which, though beautiful to the eye, are exceedingly bitter to the taste.
The people of Israel are referred to here by Moses as being utterly corrupt, bringing forth only bitter fruit.