juniper (tree)

Boyd’s Bible Dictionary:

(young producer). Not the evergreen, but the desert broom-shrub (1 Kings 19:4-5; Job 30:4; Psa. 120:4).

Concise Bible Dictionary:

This is supposed to refer, not to the juniper (see HEATH), but to the Arabic ratam, the Retama rætam, a “broom” that grows twelve feet high, under which a person could sit for shelter (1 Kings 19:4-5). In Job 30:4 reference is made to its roots being used for food by the poor. Its roots were also burnt for charcoal, and Psalm 120:4 says that sharp arrows of the mighty with coals of juniper were to be applied to a false tongue.
Retama Raetam

Strong’s Dictionary of Hebrew Words:

or rothem {ro'-them}; from 7573; the Spanish broom (from its pole-like stems)
KJV Usage:
juniper (tree)