When selecting trees for landscapes, people all too often stick with the familiar. On the surface, this makes sense. We know what we are getting when we plant a familiar tree. We've likely seen it growing somewhere else. There is likely something attractive or otherwise beneficial about it. Common trees may also be cheaper to purchase.
However, sticking with the familiar causes problems. Too much reliance on a single species/genus can have devastating effects if a pest/disease/condition severely affects the overplanted type of tree (see emerald ash borer, Dutch elm disease). Diversifying our plant profile can help buffer from these effects. Planting more species in a given area can also increase overall benefit of our urban forest, as different species provide different benefits.
Fortunately there are a number of underutilized trees that can do well in and around Chicago. Here are five such trees:
1. Kentucky Coffeetree (Gymnocladus dioicus)
Growth Rate: Slow to Medium
Mature Shape: Oval
Height: 60 to 75 feet
Width: 40 to 50 feet
Site Requirements: Prefers full sun and can tolerate a wide range of soils
2. American hornbeam (Carpinus caroliniana)
Height: 20 to 30 feet
Spread: 20 to 30 feet
Crown uniformity: symmetrical
Crown shape: oval
Crown density: dense
Growth rate: slow
Uses: sidewalk cutout (tree pit); deck or patio; specimen; street without sidewalk; screen; hedge; tree lawn 3–4 feet wide; tree lawn 4–6 feet wide; tree lawn > 6 ft. wide; Bonsai; shade
Pests - Relatively few insects attack hornbeam. Diseases - None are normally very serious.
3. Katsura tree (Cercidiphyllum japonicum)
Uses: shade; street without sidewalk; specimen; parking lot island 100–200 sq ft; parking lot island > 200 sq ft; tree lawn 4–6 feet wide; tree lawn > 6 ft wide; highway median
Height: 40 to 60 feet
Spread: 35 to 60 feet
Crown uniformity: symmetrical
Crown shape: oval, upright/erect, pyramidal, spreading
Growth rate: fast
4. Nannyberry (Viburnum lentago)
Uses: Nannyberry is a shade-tolerant, understory species useful in landscape plantings as shrub borders, taller barriers, hedges, and windbreaks.
General: Nannyberry is a native, deciduous, multi-stemmed shrub or small tree that may reach 36 ft. in height.
Nannyberry is leggy and somewhat open at maturity with an irregular to rounded crown. Suckers often form at the base. The bark is dark gray to black in a pattern of small blocks.
5. Ohio buckeye (Aesculus glabra)
Uses: recommended for buffer strips around parking lots or for median strip plantings in the highway; shade tree
Height: 50 to 70 feet Spread: 40 to 50 feet Crown shape: round Crown density: dense
Growth rate: medium
6. Japanese tree lilac (Syringa reticulata)
Characteristics: medium-sized ornamental tree or very large ornamental shrub -maturing at about 25' tall x 20' wide, although larger under optimum conditions -upright oval growth habit, becoming more rounded with age -medium growth rate.
Site: full sun to partial sun -best performance occurs in full sun in a moist, well-drained soil of average fertility, but it is highly adaptable to poor soils, compacted soils, various soil pHs, and drought.
7. American yellowwood (Cladastris kentukea)
Height: 30 to 50 feet
Spread: 40 to 50 feet
Uses: recommended for buffer strips around parking lots or for median strip plantings in the highway; shade tree; specimen; residential street tree
Pest resistance: no pests are normally seen on the tree
What are your favorite undervalued trees?