Ptelea trifoliata aka Wafer Ash

Ptelea trifoliata, or hoptree, belongs to the citrus family, Rutaceae. Its native range runs from southeast Canada through Mexico. It grows in woods, ravines, thickets, prairies, and rocky bluffs. This deciduous plant forms a large shrub or small tree. Its dense, round crown often has several main stems. Low branches and suckers help create a bushy shape. Growth is slow.

In gardens, it reaches 10–20 feet (3–6.1 metres) tall and wide. RHS gives a taller limit of 26 feet (8 metres). Its spread there is narrower, at 8–13 feet (2.5–4 metres). Young bark is smooth and gray-brown; older bark grows rough. Brown to reddish stems carry small buds with fine hairs. Alternate leaves have three leaflets, with the middle one largest. Their glossy, dark green surfaces turn yellow-green in fall. Crushed leaves have a strong smell that some find unpleasant. Tiny leaf glands show when held against bright light.

Small green-white flowers grow in clusters at the branch tips. Bloom falls in May and June, starting earlier in North Carolina. The flowers have four or five petals and an unpleasant scent. Most plants bear male or female flowers, though some flowers contain both parts. Carrion flies carry pollen between flowers. Flat, round samaras follow, each edged with a thin wing. These fruits measure about 0.08 feet (0.025 metres) across. They turn from green to tan or brown as they ripen. Hanging fruit clusters remain well into winter.

Hoptree grows in partial or deep shade and tolerates full sun. Sources differ on the best light, but agree on good drainage. It accepts clay, loam, sand, and shallow rocky ground. It also grows across acid, neutral, and alkaline soils. Moist soil suits it, but it withstands dry soil and drought. Chicago lists USDA zones 3–9; RHS rates it H6. Its low care needs suit groups, screens, and informal hedges. It also works as a specimen or beneath taller trees.

Birds and small mammals eat the fruit during the colder months. Giant swallowtail caterpillars feed on this plant. Seeds have served as a hop replacement, and roots had medicinal uses. That history does not establish safety for eating or home treatment. The species evidence also flags contact dermatitis. Serious pest and disease problems are few. Leaf spot and rust can occur; dry sites may bring spider mites. RHS notes possible honey fungus risk, but its severity remains unclear.