Superficially resembling Sumacs at first glance, the Tree of Heaven is an extraordinarily invasive tree species native to China. It is superbly well adapted to cope with almost every soil condition, drought, and many man-made roadblocks (such as concrete and air pollutants).
Ailanthus altissima (Tree of Heaven, Chinese Sumac)
Native: invasive in U.S.A., China (where these were used as a food source for silk worms)
Hardiness Zones: 4-8
Height: to 23 meters
Diameter: canopy to 18 meters
Root System: spreading, enormously extensive, possibly to 27m from parent stem
Growth Rate: extremely rapid (typically 1.8m annually, once recorded at 3.6m in one year after cutting an adult to the ground)
Age: short-lived, to 70 years max
Monoecious/dioecious: dioecious typically (separate male/female plants), some flowers perfect (monoecious)
Tolerates: drought, air pollutants
Problems (major): Trees of Heaven are incredibly difficult to control, especially since they have at most minor disease and insect problems. This tree is very invasive in the United States. These may ravage sidewalks, pavement, sewers, and other manmade structures in addition to displacing native species.
Problems (minor): powerful winds (due to weak wood)
Poisonous: These produce allelopathic/herbicidal compounds, such as ailanthone, reducing competition.
Soil requirements: grows in almost every soil type of most acidic/alkaline conditions, moisture levels, drainage, and type (sandy/loamy/clay)
Air requirements: tolerates air pollutants, grows well but dwarfed in cities
Watering requirement: low to moderate
Sun requirement: full sun to almost dense shade
Leaves: odd pinnate, 11-25 leaflets with nearly truncate base and attenuate ends, roughly trollate, veins light yellow-green and alternating, medium green, red twig, rachis, and petioles, gland-tipped basal teeth on individual leaflets yellow-green, to 60cm per leaf
Flowers: yellow-greenish, June-July, in enormous clusters
Fruits: samaras/schizocarp, oblanceolate, pink/yellow (red/brown when ripe) with yellow “eye” where seed sits, indihescent, twisting/curling at end, large terminal clusters, ripening in September, dispersed October to spring, upper estimates speculate 325,000 seeds can be produced by a single tree annually
Seeds require stratification: No, dormancy does improve otherwise slow germination though.
Seed dispersal: wind
Form: loose, open, similar to small Sumacs (Rhus sp.) in urban areas
Trunk: weak wood (susceptible to breakage by high winds), bark smooth, light gray
These can proliferate rapidly by suckering (producing offshoots) and self-seeding, may become aggressive and difficult to remove once established. These grow almost EVERYWHERE, even through slits in sidewalks and through blacktop or asphalt surfaces. Chemicals glyphosate and triclopyr may be effective if applied to shoot portion.
These were once used as ornamentals upon introduction to New York in the 1700’s, although this practice has been abandoned due to this tree’s invasive nature. The leaves are a food source for silk worms.