A noble vine. — Literally, a Sorek vine. Elsewhere rendered choice or choicest (Genesis 49:11; Isaiah 5:2). The word “Sorek” points primarily to the dark purple of the grape, and then to the valley of Sorek, between Ascalon and Gaza (Judges 16:4).
Wholly a right seed. — Literally, a seed of truth, parallel with the “good seed” in the Parable of the Tares. Here, however, as in Isaiah 5:1-7, which Jeremiah seems to have in his mind, stress is laid not on the mingling of the evil with the good, but on the degeneration which had changed the character of that which God had planted.
Art thou turned...? — Better, hast thou changed thyself ...?
Plant. — Better, branches.