Walnut Township is one of eighteen townships in Appanoose County, Iowa, United States. As of the 2010 census, its population was 894.GeographyWalnut Township covers an area of 80.0km2 and contains two incorporated settlements: Mystic and Rathbun. According to the USGS, it contains six cemeteries: Bohm, Elgin, Forbush, Highland, Shaeffer and Zimmer.