Which plants grow in the colder upper Rio Grande region?

In the colder upper reaches of the Rio Grande, the vegetation varies significantly based on elevation and climate.

At its highest sources in the San Juan Mountains, the river flows through forests characterized by spruce, fir, and aspen trees. As the river moves into the cooler, higher-elevation areas of northern New Mexico and the San Luis Valley in Colorado, the landscape transitions into a cold steppe climate. This region supports vegetation such as piñon pine, juniper, and sagebrush.1

These plant communities are distinct from the hot desert flora, such as mesquite, creosote bush, cactus, and yucca, that characterize the lower, more arid portions of the river's course.1