In the middle part of the 20th century, Screwbean Mesquite bosques (Spanish for forest) were one of the dominant forest types in riparian systems of the southwest, comprising over a third of riparian vegetation along the Lower Colorado River and adjacent tributaries. These trees produce a distinctive seed pod that is an abundant and nutritious food for animals as well as people. Native peoples of the southwest used the screwbean as a source of food, building material and firewood.