Tree of Heaven or Hell?

As with so many invasive non-native plants, Ailanthus altissima was introduced as an ornamental species. First imported from China to Europe in the 1700s, this deciduous tree has been widely planted in parks, gardens and public spaces. The name is derived from the Ambonese word ailanto, meaning "heaven-tree" or "tree reaching for the sky”.  But it seems that a more appropriate name for the plant might actually be Tree of Hell. Here is why…

Tree of Hell

Ailanthus altissima is an aggressive invader of disturbed and urban habitats such as roadsides, railways and brown field sites. The tree is tolerant of pollution and poor soil quality, which may have otherwise prevented its spread. In South-western Virginia, the Tree of Heaven has infested 30% of the interstate highways, reducing both road visibility and road safety.  

In the UK, Ailanthus altissima is found in urban areas where it has been purposefully planted, confining its distribution to areas of low conservation value. However, in the warmer climates of southern Europe this “Tree of Heaven” has invaded both woodlands and pastures. Once established, the tree forms dense thickets through prolific root and stump sprouting; displacing native vegetation. Its roots can stretch for 15 metres away from the existing stems!

Ailanthus altissima maintains its dominance using allelopathy – producing a toxic compound called Ailanthone. This compound has herbicidal properties, suppressing the growth of surround native vegetation. Ailanthone also has phytotoxic properties, causing mild Dermatitis (similar to Giant Hogweed).

It is no surprise that the Tree of Heaven is listed as one of the worst 100 invasive species in Europe (DAISIE). Don’t forget, you can record sightings of this species using our free Smartphone app – That’s Invasive!

References 

http://www.nonnativespecies.org/factsheet/factsheet.cfm?speciesId=101

Burch, P. L & Zedaker, S. M (2003). 'Removing the invasive tree Ailanthus altissima and restoring natural cover' Journal of Arboriculture 29: 18 - 24

Heisey, R. M (1996). ‘Identification of an Allelopathic Compound from Ailanthus altissima (Simaroubaceae) and Characterization of its Herbicidal Activity’ American Journal of Botany 83: 192 -200

 Photo Credits: Tree of Heaven (RPS Group Plc); Tree of Heaven seeds (Luis Fernández García)