Boyd’s Bible Dictionary:
(dark berry). Translation disputed (2 Sam. 5:23-24; 1 Chron. 14:14). The bacah or balsam tree is probably meant.
Concise Bible Dictionary:
The word baka is supposed to be from a root signifying “weeping,” and to refer to some tree that distils an odoriferous gum; but what tree is alluded to is unknown. David was to wait for some secret sign from God in the mulberry trees before attacking the enemy (2 Sam. 5:23-24; 1 Chron. 14:14-15; Psa. 84:6 margin). The true mulberry is supposed to be the tree called in the AV Sycamore.