CREOSOTE-BUSH (Larrea tridentata or Covillea glandu losa), a North American shrub of the caltrop family (Zygophyl laceae), called also greasewood, native to hot arid regions in the southwestern United States and adjacent Mexico. It is an evergreen, rank-smelling, diffusely-branched shrub, 2 ft. to 5 ft. high, with brittle stems and very leafy branches. The small, olive green, copiously resinous leaves emit a strong tarry odor. The bright yellow flowers, a half-inch across, appearing in early spring, are followed by small densely white-woolly globose seed-vessels. At low altitudes and sometimes up to 3,00o ft. the creosote-bush is often a very abundant shrub, forming, in the Mohave, Colorado, Gila and similar deserts, a characteristic zone of vegetation called the "Larrea belt."