Arboretum West southwest of the Sewell Hall contains native trees and plants found on an east-west transect of California along Interstate 80 — from the coastal redwoods to the giant Sierra redwoods and the deserts. A brief walk will take you to plants typical of cooler and higher climate zones. A recent addition is a vernal pool that is home to plant life unique to these temporary environments.
Arboretum East by the greenhouse contains plants and specimen trees from other parts of the country and the world that are important to foresters and landscapers.
Additionally, there are trees around Sewell Hall which are valuable as teaching aids for science courses.
For more, the Sierra College Biology Department also has web pages on both arboretums.