Coffman Viburnum Walk

“They (viburnums) comport themselves with understated dignity, the sum of all their seasons greater than their parts. A viburnum exists for virtually every garden…” Michael Dirr.

As Michael Dirr, professor of horticulture and author of the manual of woody plants has stated, viburnums are truly a plant for all seasons. The genus Viburnum may be one of the most interesting and yet complicated taxa to identify. Morphological characteristics such as habit, leaves, inflorescences, buds, flowers, and fruits are key to plant identification, but with viburnums, no set characteristic can be applied across all species. As Michael Dirr explains, the only two features that aid in the identification of such a vast genre is the fact that the fruit is a drupe and the leaves have opposite arrangement. Viburnums can have a tree or shrub habit. They can be deciduous, semi-evergreen, or evergreen. Some are large, growing up to 60 feet tall, with others being more compact and only reaching two to three feet in height. The leaves of a viburnum can be serrated, dentate, or lobed, with pubescence or without. Buds can be glaborous, naked, or pubescent, as well as red, green, or brown. While the flowers are mostly white, some also have hues of pink. The species of viburnum may be well known to the average gardener because of its fragrant smell in the spring; most likely the species and cultivar Viburnum carlesii ‘Korean Spice’. However, other types can be foul smelling, or simply have no odor at all. Fruit color can be black, purple, blue, red, orange, or yellow. According to scientific literature, there are anywhere from 160 to 250 species of viburnum. Around 20 species are native to North America, with the vast majority of the taxa from Asia. As a result, true identification and representation of such a diverse genre is best understood on a molecular level.

The Iowa Arboretum established the species-specific viburnum collection 2008, in honor of Dr. Eugene Coffman, a native of Iowa, and improbable viburnum collector, to say the least. Practicing  medicine in Dubuque, Iowa, Gene and his wife Bobbie commenced their love of viburnums when a patient of his was hired to landscape around their home in 1961. As the story goes, Gene was automatically hooked on viburnums thereafter, turning his yard and passion for woody plants into the development of Ridge Road Nursery near Bellevue, Iowa. A particular fondness for viburnums led him to amass one of the largest collections in the Midwest and Viburnum sieboldii ‘Wavecrest’ became his signature plant. Its leaves are much larger and more ridged than those of the species (which can be found in the Founders’ Grove).

Ridge Road Nursery donated this particular collection to the Arboretum, which is currently comprised of cold-temperate North American viburnums and their Asian cousins. The goal of this collection is to showcase how variable and widely adaptable this woody shrub can be; ultimately, introducing an appreciation and love for viburnums to every gardener.

In 2022, a trio of Viburnum dentatum ‘Chicago Lustre’ was planted at the south end of the viburnum walk and a similar trio of Viburnum wrightii ‘C.A. Hildebrandt’s’ was added at the north end.