River Forest is home to such varieties as Zelkova, Beech, Paperbark Maple, Black Tupelo, Katsura, Filbert, Larch, Dawn Redwood, Bald Cypress, Cucumber Magnolia, Alder, Amur Maackia, more than a dozen varieties of Elm and even thornless and fruitless Osage Orange.  They also protect and maintain approximately 225 ash trees of different varieties.

In 2002, River Forest was one on the first communities in the Chicago area to plant the Triumph Elm on parkways as a trial before Dutch Elm Disease resistant varieties of elm were commercially available.  The Triumph Elm was developed at the Morton Arboretum through the research of Renowned Tree Scientist, Dr. George Ware.  Since that time, River Forest has followed the research of Dr. Ware and others from the Morton Arboretum and that research has help them develop their own very diverse arboretum.