Strombocarpa pubescens

Strombocarpa pubescens, commonly known as Screwbean Mesquite or Tornillo, is a species of flowering shrub or small tree in the pea family, Fabaceae, that is native to the southwestern United States (Texas, Arizona, New Mexico, California, southern Nevada and Utah) and northern Mexico (Baja California, Chihuahua, Coahuila, Sonora). In California it is found primarily in desert areas from Inyo County southward. It has light brown bark, usually short, straight spines (1-3 centimeter/0.39-1.2 inches), twice-compound leaves, and numerous, small, yellowish flowers appearing in elongate spikes. It is found along streams and valleys in deserts, particularly in damp or saline soil, and grows to about 7 meter (23 feet). It is distinguished from the very similar Honey Mesquite (Prosopis glandulosa) by its tightly twisted seedpods (legumes) which very much resemble turned screws. This morphology may have been an evolutionary defense against seed predators such as bean weevils (Bruchinae). Like Honey Mesquite, these seed pods are valued by wildlife and were eaten by native people.