An arboretum is a botanical garden dedicated to TREES and other woody plants. ARBORETUM SIGHTS is a crossword solution that refers to the TREES that can be seen in an arboretum. The answer to this clue is TREES, which is a five-letter word. TREES are the main feature of an arboretum, and they come in many shapes, sizes, and varieties. Visitors to an arboretum can enjoy the beauty of the TREES, as well as learn about their different characteristics.