Ptelea trifoliata

Ptelea trifoliata, commonly known as common hoptree, wafer ash, stinking ash, and skunk bush, is a species of flowering plant in the citrus family (Rutaceae). It is native to North America, where it is found in Canada, Mexico, and the United States. It is a deciduous shrub or tree, with alternate, trifoliate leaves.

Description

A very small tree. It grows up to 8 m tall. The trunk is 15 cm across. The trunk is often branched. The crown is irregular and rounded. It loses its leaves during the year. The leaves are alternate and compound. There are 3 leaflets and the main stalk is 10-15 cm long. The leaflets are 10-15 cm long. They have a sharp point. They narrow below the middle. The upper surface is dark shiny green and it is paler underneath. It has a lemon smell when crushed. The flowers are small and greenish-white. They are in clusters at the tips of the shoots. The male and female flowers are separate usually on separate trees. The fruit are flat and 1-2 seeded. There is a wing around the seed case. This is 25 mm across.

Edible Uses

The fruit has a very bitter flavour, though it is eaten by young children. It is also used as a hop substitute in beer-making and added to yeast to help it rise more quickly when making bread. The fruit is produced abundantly in Britain, though very little of it is fertile; it is very thin and around 25mm long.

Traditional Uses

The bitter fruit have been used as a substitute for hops in flavouring beer. They also make yeast rise more rapidly. The fruit have also been ground and used as a condiment.

Medicinal Uses

The root-bark is anthelmintic, antibacterial, antiperiodic, stomachic, and tonic. It has been combined with other medicines to increase their potency. It soothes mucous membranes and promotes appetite, and is tolerated when other tonics cannot be retained. It is taken for intermittent fevers such as malaria, heartburn, roundworms, pinworms, and poor digestion, and applied externally to wounds. Roots are harvested in autumn, the bark peeled off and dried for later use. A root preparation is also used for asthmatic breathing, fevers, and poor appetite. The leaves are said to be useful for treating wounds and destroying intestinal worms.

Known Hazards

This species can cause photosensitization of the skin.

Distribution

It is native to E. North America. It grows along shorelines and on dry rocky soils. It can tolerate part shade. It flowers only in full sunlight. It suits hardiness zones 5-10.

Where It Grows

Australia, Canada, Central Asia, Europe, France, Germany, Hungary, Mexico, North America*, Romania, Slovenia, Tajikistan, USA,

Cultivation

Succeeds in any fertile well-drained moisture retentive soil in full sun or light part day shade. The young growth in spring can be damaged by late frosts. A very ornamental plant, it is slow-growing and short-lived in the wild. The sub-species P. trifoliata mollis. Torr.&Gray. is the form that is eaten by children. The leaves are aromatic. All parts of the plant emit a disagreeable odour. The flowers are especially pungent and are pollinated by carrion flies. Plants in this genus are notably resistant to honey fungus.

Propagation

Seed is best sown as soon as it is ripe in a cold frame. Stored seed requires 3 months of cold stratification at 5°C and should be sown as early in the year as possible. When large enough to handle, prick seedlings out into individual pots and grow on in light shade in a cold frame for at least their first winter, then plant out into permanent positions in late spring or early summer after the last expected frosts. Very little seed produced in Britain is viable. Half-ripe cuttings can be taken in July/August in a frame. Layering is also possible.

Other Uses

Sometimes used as a hedge plant in North America. The wood is hard, heavy, and close-grained, weighing 51lb per cubic foot, though the tree does not grow large enough for commercial exploitation.

Notes

There are about 10 Ptelea species.

Also Known As

Krilatec, Pinacatillo

References (15)

• Coombes, A.J., 2000, Trees. Dorling Kindersley Handbooks. p 284
• Cundall, P., (ed.), 2004, Gardening Australia: flora: the gardener's bible. ABC Books. p 1105
• Facciola, S., 1998, Cornucopia 2: a Source Book of Edible Plants. Kampong Publications, p 221
• Farrar, J.L., 1995, Trees of the Northern United States and Canada. Iowa State University press/Ames p 230
• Grandtner, M. M., 2008, World Dictionary of Trees. Wood and Forest Science Department. Laval University, Quebec, Qc Canada. (Internet database http://www.wdt.qc.ca)

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