The Klehm family purchased the nursery in 1968 and maintained it until 1985, when they donated the property to the Winnebago County Forest Preserve District as an arboretum.

The arboretum includes a pre-settlement Bur Oak grove (5 ha / 12 acres) whose largest trees are estimated to be over 300 years old.

The East Asian collection includes Cork Trees, Japanese Red and White Magnolia, Flowering Quince, and various Honeysuckles.

The Northern America collection includes American Beech, Yellow Buckeye, Cucumbertree Magnolia, Tulip Tree, Ponderosa Pine, Colorado Spruce, and Douglas Fir.

Other woody plants include Basswood, Red Buckeye, Black Cherry, American Chestnut, Dogwood, Fringe Tree, Hackberry, Hemiptelea, Japanese Pagoda Tree, Shagbark Hickory, Umbrella Magnolia, Scarlet Oak, White Oak, Redbud, Carolina Silverbell, Sourwood, Sweetgum, Viburnum, Black Walnut, and Wisteria.