Ailanthus altissima (Mill.) Swingle
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Ailanthus altissima is a tree.
Ailanthus altissima was already described and the name validly published by Philip Miller. It was Walter Tennyson Swingle, however, who reclassified it into todays valid botanical systematics in 1916.
The trees are comparatively fast-growing and short-lived. They reach heights of 20 to 25 metres, have a rounded to broadly columnar canopy and spread rapidly. The main growing season is in spring and summer. The plants reach a width of 10 to more than 15 metres.
Wood and Bark
The bark is smooth and silver-grey to white.
Ailanthus altissima is deciduous. The dark-green, imparipinnate leaves are alternate. The ovate-lanceolate leaflets are entire and petiolate. The surface of the leaves is glandular. They turn an attractive yellow in autumn.
Flowers and Fruits
Ailanthus altissima produces showy panicles of erect, greenish yellow five-stellate flowers in July. The plants flower on older shoots. They are dioecious, pollination takes places by allogamy through animals.
From summer to autumn the trees produce an abundance of ornamental yellow samaras that are persistent on the plant.
The plants form shallow roots.
Ailanthus altissima is native to China.
The trees prefer a sunny to half-shady situation on dry to moderately moist soil. The substrate should be sandy, gritty-sandy, sandy-loamy, gritty-loamy, sandy clay, loamy clay or peaty and comparatively poor with a pH between 4,1 and 7,9. The plants need a soil depth of at least 76 centimetres for good growth. They tolerate temperatures down to -23Â°C (USDA zone 6) and need a frost-free period of at least 21 weeks.
Classification after Prof. Dr. Sieber
- open areas
Tolerance of special soil conditions
- medium: soil salinity, anaerobic soil, drought
- high: calcareous soil, city climate, road salt
The ornamental value of Ailanthus altissima lies especially in its fragrance. The recommended planting distance is 3,5 to 4 metres. Suited for rooftop gardens, as well as suited as avenue tree, container plant, specimen plant, greenery along roads, bee pasture, bird pasture and as plant providing shelter for birds. From a commercial point of view the trees can be used to produce veneer. The plants have only low potential for fuelwood production.
Maintenance and Propagation
The plants can be considered rather high-maintenance.
- Plants can be cut back down to the trunk (coppicing) as necessary.
Propagate by sowing. The seeds require vernalization. Also by cuttings.
Ailanthus altissima is moderately toxic.
Please read the health issues note!
Pests and Diseases
Irregular swelling, so-called 'galls', may be caused by insects, mites, fungi or bacteria. Destroy affected parts. To prevent infection avoid injuring the plants and improve drainage.
Brown, orange or yellowish pustules on shoots and on the leaves lower surfaces are very likely caused by a fungal infestation (rust). Remove affected parts and apply fungicide. Also improve ventilation and reduce humidity.
- Walter Erhardt, Erich GÃ¶tz, Nils BÃ¶deker, Siegmund Seybold: Der groÃe Zander. Eugen Ulmer KG, Stuttgart 2008, ISBN 978-3-8001-5406-7. (Ger.)
- Christoper Brickell (Editor-in-chief): RHS A-Z Encyclopedia of Garden Plants. Third edition. Dorling Kindersley, London 2003, ISBN 0-7513-3738-2.