An arboretum feature is composed of two elements: SHADE and tree. SHADE is a five-letter word that refers to the protection from direct sunlight, while tree is a four-letter word that refers to a woody perennial plant. SHADE is important in an arboretum because it provides relief from the sun and helps protect the trees from extreme temperatures. Trees are also essential components of an arboretum, as they provide a habitat for wildlife and can be used to create a beautiful landscape.