Holly Dolly is section of the traditional Finnish folk song "Ievan Polkka" (sometimes misspelled Levan Polka) sung by the Finnish quartet Loituma. There has been some confusion concerning the exact nature of the vegetable in the animation. In the Japanese version of the anime, it is identified as a Welsh onion, but the American dub identifies it as a leek, from which the name of the animation is derived.