Smith's Bible Dictionary (1863)
” (Exodus 12:8) These “bitter herbs” consisted of such plants as chicory, bitter cresses, hawkweeds, sow-thistles and wild lettuces, which grow abundantly in the peninsula of Sinai, in Palestine and in Egypt. The purpose of this observance was to recall to the minds of the Israelites their deliverance from the bitter bondage of the Egyptians.
Hastings' Dictionary of the Bible (1898) & Schaff's Bible Dictionary
BITTER HERBS . Ex 12:8. The Jews were commanded to eat the Passover with a salad of bitter herbs; and the Rabbins tell us that such plants as wild lettuce, endives, and chicory were employed for that purpose, as they still are by the Arabs in those regions. The use of them on that occasion was intended to call to their remembrance the severe and cruel bondage from which God delivered them when they were brought out of Egypt.