Weeds in our Area (Part Thirty One)

By Bob and Ena McIntyre – Garden Route Branch.

Tree of Heaven (Ailanthus altissima)

Tree of Heaven (Ailanthus altissima) is a very large (10 – 15m), very invasive deciduous tree commonly seen as vigorous young saplings sprouting profusely from root suckers. In Wilderness many can be seen in the proximity of their huge parents along Constantia Drive opposite the Church in the grounds of the now demolished hotel annex. Originating from China these trees were cultivated primarily as ornamentals. Suitable only for very large gardens and even then its spreading roots create problems by suckering wherever they are cut, clearly makes it totally unsuitable for any typical residential site. The plant’s invasive status is that of potential transformer – it is a declared invader (cat 3). It invades forest margins, roadsides and rivers in cool moist regions such as ours and can be spotted in several places around the village. In addition the leaves and flowers are poisonous as well as being a skin irritant.

Identification: A. altissima is deciduous only for a very short period and is easily recognised by its bold, compound pinnate leaves that are dark green in colour. The flowers are greenish-yellow and appear in large terminal sprays during Oct – Nov and the seeds are striking rust red. At a glance it is possible to mistake the tree of Heaven for the Indian Mahogany (Cedrela toona)

Control: Control of this fast growing and vigorous suckering specimen will require tenacious and persistent effort. Cut stump treatment of any saplings will in all probability be the best solution. Left unchecked this species will undoubtedly become a major headache for you and your neighbours.

Substitute: Rooi essenhout (Trichelia emetica) a fast growing tree with a non-invasive root system or Wild peach (Kiggelaria africana) also with non-invasive roots. Both trees provide excellent shade and are firm favourites with our feathered friends.

Line drawing with acknowledgements to “ALIEN WEEDS AND INVASIVE PLANTS” by Lesley Henderson. Copyright © 2001 Agricultural Research Council.