ChristianAnswers.Net WebBible Encyclopedia
There are 4 Hebrew words translated as “herb.”
Hebrew: 'eseb, any green plant; herbage (Genesis 1:11-12, 29-30; 2:5a; 3:18, etc.); comprehending vegetables and all green herbage (Amos 7:1-2).
Yarak, green; any green thing; foliage of trees (2 Kings 19:26; Psalms 37:2); a plant; herb (Deuteronomy 11:10).
Or, meaning “light” In Isaiah 26:19 it means “green herbs;” in 2 Kings 4:39 probably the fruit of some plant.
Merorim, plural, “bitter herbs,”; eaten by the Israelites at the Passover (Exodus 12:8; Numbers 9:11). They were bitter plants of various sorts, and referred symbolically to the oppression in Egypt.