We still call them marshmallows, but there's no marsh mallow in them anymore. Candy made with honey and thickened with sap from the root of the marsh mallow (Athea officinalis) plant was savored in ancient Egypt. Marsh mallow, the plant, grows to be two to four feet tall. It has gray-green leaves and pink flowers. Not surprisingly, it grows in marshes and is related to other "mallow" plants, such as the rose mallow, the apricot mallow, and the common mallow.Link (via Making Light)
Up until the mid-1800s, marshmallow candy made in the United States contained marsh mallow sap as a thickener. Today's recipes use gelatin (made from animal bones and hides) instead of the sap. Mostly, though, marshmallows are made of corn syrup or sugar. Gum arabic (made from acacia trees) serves as a "foam stabilizer." Flavoring is also added.
Update: Michael sez, "I would like to point out that the basic ingredient of a banana split is from New Guinea, not Malaysia:
Indeed, new evidence arising from archaeological and palaeoenvironmental studies at Kuk Swamp in the Western Highlands Province suggests a very long history of banana cultivation in Papua New Guinea dating back to at least 7000 years ago and possibly as long ago as 10 000 years (Denham et al. 2003). This is the longest record for banana cultivation in the world.