Many visitors are surprised at the amount of vegetation in Canyonlands. Plants are critical components to all ecosystems, and Canyonlands is no exception. Plants capture particulate dust in the air, filter gaseous pollutants, convert carbon dioxide to oxygen, provide animal habitat and possess many raw materials useful to humans. Visitors encounter a variety of plant species from tiny lichens clinging to sandstone to stately cottonwoods growing in canyon bottoms. Wildflowers bloom in spring, cacti appear among knobby biological soil crust, and bunch grasses grow throughout the open country. These varied communities and ecosystems allow scientists to research how plants adapt to a changing world.