I would like to continue with Dave's line of thinking on this. We all know that wheat is a grain plant. Tares/darnel is a ryegrass which looks much like wheat in its early stages of growth, but is not edible. The 'chaff' is not a plant, but the husk, a dry, scaly protective casing of the wheat grain. Chaff is not edible, nor desirable with the wheat, so it is remove. One way to get rid of the chaff is by thrashing, since it is light and fluffy and blows away easily and then it's piled up and burned.
So in the parable, the wheat is the elect and the tares are those who come among us, but are not truly converted. The chaff represents the unwanted part on the wheat/elect and is the same thing as the wood, hay and stubble mentioned in Scripture.
1Co 3:12-13 And if anyone builds on this foundation gold, silver, precious stones, wood, hay, stubble, each ones work shall be revealed. For the Day shall declare it, because it shall be revealed by fire; and the fire shall try each ones work as to what kind it is.
So in the parable the chaff of the wheat is like that being spoken of here in 1 Cor. "wood, hay, stubble," it's represents a person undesirable 'works' and that's the part that needs to be removed and burned.
1Co 3:14 If anyone's work which he built remains, he shall receive a reward.
v. 15 If anyone's work shall be burned up, he shall suffer loss. But he shall be saved, yet so as by fire.
mercy, peace and love
Kat