Tree of Heaven (Ailanthus altissima, (Mill.) Swingle)
Origin: Northern and Central China
Size: up to 20 metres in height
The Tree of Heaven is a deciduous tree, can grow up to 20 metres in height. The bark is smooth, grey with pale stripes; forms shoots directly from the root. The leaves are long, pinnate, and compound, containing 10 to 41 leaflets organised in pairs; the young leaves have reddish tips. The flowers are unisexual, small and yellow- greenish gathered in panicles; the male flowers have an unpleasant odour. The fruit is a spirally-twisted samara with one seed, light reddish-brown, growing in clusters.
The Tree of Heaven is native to warm and temperate regions of China; it prefers moist and loamy soils, but is adaptable to a wide variety of soil conditions and can tolerate a wide range of climatic conditions, although does not tolerate deep- shade and flooding. Outside its native range it can grow in forest margins, roadsides, river banks, old fields, scrublands, pine and oak forests.
This species was introduced in Europa in the 1740’s for ornamental purposes, in the USA in 1784 and become extensively naturalised. Nowadays can also be found, in Australia, South Africa, India, Japan and several other Asian countries. In Portugal it is considered an invasive species due to its prolific fruiting, rapid grow rate, ready germination and adaptability to infertile soils. This species also produces alellopathic chemicals which stops other species growing.
In China, the leaves, roots and bark are used in traditional Chinese medicine and has been grown in several parts of the world as a host plant for the Ailanthus Silk Moth (Samia cynthia), a moth involved in silk production.