Manna is an edible substance that, according to the Bible, God provided for the Israelites during their travels in the desert following the Exodus and prior to the conquest of Canaan. The word "manna" means "what is it?" in Hebrew, and it was described as being like coriander seed, white, and tasting like wafers made with honey. The Bible does not discuss the chemical composition of manna, but it is believed to have been literal bread that God caused to miraculously appear each morning during the Israelites wilderness wanderings. The miracle of manna ceased shortly after the Israelites entered the Promised Land.
In a modern botanical context, manna is often used to refer to the secretions of various plants, especially of certain shrubs and trees, and in particular the sugars obtained by evaporating the sap of the manna ash, extracted by making small cuts in the bark. The manna ash, native to Southern Europe and Southwest Asia, produces a blue-green sap, which has medicinal value as a mild laxative, demulcent, and weak expectorant. The physicians of the Arabian and Latin Middle Ages held that manna was a dew falling on stones and trees, and that it was sweet like honey.
Today, "manna" is still harvested and used in parts of Iran and Iraq, and the word refers to either sweet sap of any plant (tree or bush) that appears in the region or the secretion from insects that feed on trees.
