Introduction
This cultivar of the deciduous North American native tree reaches 15 feet in height with a spread of 10 to 15 feet and forms a broad, rounded canopy over a slender, grey trunk. The trifoliate, four- to six-inch-long leaves are glaucous blue-green in summer, turning yellow in fall before dropping. Inconspicuous greenish-white flowers appear in terminal clusters in June and July, their presence easily detected by the delicious orange blossom-like perfume. The blooms are followed by interesting, one-inch-diameter, flattened, tan "wafers" which will persist on the tree if not first consumed by wildlife. In the past, this bitter fruit was used as a substitute for hops in brewing beer.
General Information
Scientific name: Ptelea trifoliata
Pronunciation: TEE-lee-uh try-fole-ee-AY-tah
Common name(s): 'Glauca' common hoptree, 'Glauca' wafer-ash
Family: Rutaceae
USDA hardiness zones: 4A through 9A (Figure 2)
Origin: native to North America
Invasive potential: native cultivar
Uses: specimen; deck or patio; container or planter
Description
Height: 5 to 15 feet
Spread: 10 to 15 feet
Crown uniformity: irregular
Crown shape: round, vase
Crown density: moderate
Growth rate: moderate
Texture: medium
Foliage
Leaf arrangement: alternate (Figure 3)
Leaf type: trifoliate, odd-pinnately compound
Leaf margin: entire, serrate
Leaf shape: ovate, elliptic (oval), oblong
Leaf venation: brachidodrome, pinnate
Leaf type and persistence: deciduous
Leaf blade length: 2 to 4 inches
Leaf color: blue or blue-green
Fall color: yellow
Fall characteristic: showy
Flower
Flower color: white/cream/gray
Flower characteristics: not showy
Fruit
Fruit shape: round
Fruit length: 0.5 to 1 inch
Fruit covering: dry or hard
Fruit color: brown
Fruit characteristics: attracts squirrels/mammals; showy; fruit/leaves not a litter problem
Trunk and Branches
Trunk/bark/branches: branches droop; not showy; typically multi-trunked; thorns
Pruning requirement: needed for strong structure
Breakage: resistant
Current year twig color: brown
Current year twig thickness: medium
Wood specific gravity: unknown
Culture
Light requirement: full sun, partial sun or partial shade, shade tolerant
Soil tolerances: clay; sand; loam; acidic; slightly alkaline; well-drained
Drought tolerance: high
Aerosol salt tolerance: unknown
Other
Roots: not a problem
Winter interest: no
Outstanding tree: yes
Ozone sensitivity: unknown
Verticillium wilt susceptibility: unknown
Pest resistance: resistant to pests/diseases
Use and Management
One of a few small trees which performs well in deep shade. Plant it close to the patio or deck or locate it in a shrub border for fragrant flowers and yellow fall color display. Its native habitat is dry, rocky upland sites making it well-suited for non-irrigated landscapes.
Naturally found in the shade along the edges of woods, especially on rocky slopes in the Mississippi Valley, wafer-ash can be planted in full sun to deep shade and prefers well-drained, fertile, moist soil. While plants are better off if not exposed to extremes of wetness or dryness, wafer-ash is drought-tolerant once established. Transplants readily from the field.
Other cultivars include: 'Aurea' with yellow foliage through the spring and into the summer.
Propagation is by budding, layering, or grafting.
Pests and Diseases
No pests or diseases are of major concern although it is occasionally bothered by tree-hoppers, leaf spot, and rust.
