Ailanthus
Sponsor
Kindly sponsored by
Peter Hoffmann
Credits
Owen Johnson (2025)
Recommended citation
Johnson, O. (2025), 'Ailanthus' from the website Trees and Shrubs Online (treesandshrubsonline.
Family
- Simaroubaceae
Common Names
- Trees of Heaven
About six species of tree, sometimes very tall. Twigs with a central pith. Leaves evergreen or deciduous, alternate, pinnate, often malodorous, to c. 1 m long, with 13–41 leaflets carried in more or less opposite pairs, usually with a terminal leaflet; leaflet base oblique, margin entire or toothed. Trees usually individually male or female; flowers small, in axillary or terminal thyrses. Sepals and petals 5(–6); stamens 10(–12), styles 2–5. Fruit a samara with an oblong-elliptic aerodynamic wing, often yellow or red, surrounding the single small seed, clustered 2–5 together within a large pendulous panicle. (Brizicky 1962; Li 1993; Harden 2002; Peng & Wayt Thomas 2008).
The six species of Ailanthus recognised by Royal Botanic Gardens, Kew 2024 are distributed from northern China southwards to India and through Indonesia to northern Australia. In this taxonomy, just one of these species, the Chinese A. altissima (Mill.) Swingle, is hardy; it is the only deciduous member of its genus and is also distinguished by one to eight large teeth near the base of its otherwise entire leaflets, which carry nectar-producing glands underneath their tips. The nearest relatives of the genus are also tropical, although Picrasma also includes one hardy and deciduous member from Asia, P. quassioides (D. Don) Benn. Fossil Ailanthus have been recorded from the Miocene Epoch in Europe and North America (Wikipedia 2024).
René Desfontaines derived the name Ailanthus from the native name from Ambon Island in Indonesia for White Siris (A. integrifolia Lam.), which can be translated as ‘reaching heaven’; like many species from the south-east Asian tropical rainforest, A. integrifolia is a very tall tree, capable of attaining 60 m (Singapore National Parks Flora and Fauna Web 2024; Jacobson 1996). Thus the specific name of A. altissima, meaning ‘tallest’, is not particulary appropriate, having originally been used by Philip Miller to describe the species within the smaller-growing genus Toxicodendron. The English vernacular derivation ‘Tree of Heaven’ also seems liable to raise unrealistic expectations.
The widespread invasivity of Ailanthus altissima, at least in its var. altissima, makes it a subject of great concern and its cultivation should not be contemplated or encouraged.
