Tamarisk
A non-native, water-loving shrub along southwestern rivers, and a target of restoration work.
Tamarisk is a water-loving Mediterranean shrub that arrived in North America in the 1800s, first as an ornamental, and was later planted to slow erosion along the Colorado River in Arizona. The National Park Service says it has since spread to all of the Colorado's tributaries.
The park service says dense stands increase fire frequency, lower plant and animal diversity and change how streams behave, and that their shade keeps cottonwood seedlings from growing. Courthouse Wash in Arches is one of several places the park has worked to control it, and removal there has helped native cottonwoods.
Seeing it
Its feathery foliage lines many canyon-country waterways.