A gallery forest grows along the banks of a river in open savanna and prairie country. Sometimes, but not always, the trees on either side intertwine their canopies, forming a tunnel-like corridor over the water. (The term is adapted from the Spanish word galería, meaning an overhanging balcony.) Historically, gallery forests provided shade, fuel, refuge, and a source of food and water for people crossing huge, daunting spaces. They also served (and still do) as conduits by which wildlife migrate back and forth between wetter climates east of the hundredth meridian and drier locales on the High Plains.