Before the day of automobiles, all the peoples who traveled through Big Bend routed their trails from water to water. On the way to Oak Spring you can sit in the shade of a Comanche marker tree, a great oak bent in a bow with all its branches growing upright. Comanches marked a good campsite by tying a sapling down; with maturity it naturally assumed a horizontal or bowed position. [Illustration: Who said the desert’s palette must be dull? Desert locusts show vivid greens and yellows.] As Big Bend opened to ranching, the need for more watering places grew. Ranchers drilled wells, put up windmills, and scraped out stock tanks. Some of these waterholes remain to this day. The wells at Dugout Wells and the Sam Nail Ranch are still maintained. Without regular care such improvements would soon disappear in the desert. One of man’s inadvertent “improvements,” the tamarisk or salt cedar, has proved an unwelcome water guzzler. The tree is about the size of an ordinary apple tree, but it loses to the atmosphere about five times as much moisture as an apple tree does. In desert country where water is so scarce, tamarisks pose a serious problem. Brought to this country from the Mediterranean area for use as a windbreak, salt cedar escaped cultivation and spread like wildfire across the Southwest, invading river bottoms, drainage ways, and waterholes in unbelievable numbers. The tamarisk spreads by runners and apparently reaches isolated springs when mammals and birds bring seeds in on their fur and feathers. Growing at the rate of nearly 2 meters (8 feet) in a summer, the deep-rooted tamarisk uses up a disproportionate amount of water and actually lowers the water table. It is useless to man, and wildlife does not browse it because it tastes so salty. Big Bend National Park conducts a tamarisk eradication program as a water conservation measure centered about the springs. It is hot, dirty, time-consuming work because tamarisks are almost impossible to kill. No known creature can be used for control, and if you leave so much as a root hair, another tree will grow. You have to saw the tree off and paint the stump with a special approved chemical that does not harm other plants or wildlife and will not contaminate the spring. This effort to save the precious amounts of moisture stored in the Big Bend landscape requires constant vigilance and back-breaking effort. Big Bend Ranching Days