These are the competing Ector , Langtry , Olmos , and Zorra series. Ector soils occur at higher elevations along the northern and eastern most occurrence of Amistad soils. Langtry, Olmos, and Zorra soils are on similar surfaces. Langtry soils are along the western fringes of occurrence of Amistad soils. Olmos and Zorra soils border the southern areas of Amistad soils.
Native vegetation is short and mid-grasses, mainly gramas, tridens, and threeawns.
Shrubs are juniper, lotebush, dalea, guajillo, blackbrush, and cenizo. Mainly in southwest Texas. Series is of moderate extent. These soils were formerly included with the Ector series.