Plants - Tree of Heaven

Tree of Heaven (Ailanthus altissima (Miller) Swingle)

An early Chinese saying refers to spoiled children as "good for nothing ailanthus sprouts." (17)

DESCRIPTION: Tree of heaven is a small to medium sized tree in the Quassia family that is a persistent and aggressive weed throughout much of Europe and North America. Its deciduous leaves are odd-pinnately compound with 11-41 leaflets; their shape is lanceolate and each leaflet has a prominent dark green gland on the underside near the apex. Leaflets are each 7.5-12.5 cm (3-5 in) long and 2.5-5.0 cm (1-2 in) wide. Ailanthus reproduces from both seed and root sprouts. Sprouts may emerge up to 15 m (50 ft) from the nearest existing stem. (17) The flowers are unisexual or bisexual and are borne in large terminal clusters in the summer months. One tree can produce up to 350,000 seeds per year; these seeds are easily windblown a great distance and a high percentage of them remain viable. (18) These seeds can germinate in a wide variety of disturbed habitats, including urban and suburban areas and along railroad tracks. This species is known to have a tolerance for polluted environments and poor soils. Ailanthus is moderately tolerant of shade; in natural stands reproduction is primarily by sprouting. The species is relatively resistant to insect predation. (19) The trees are typically short-lived (30-50 years), though some have survived for over 150 years. All parts of the tree, especially the flowers, have a strong, offensive odor when bruised or crushed, which some have likened to peanuts or cashews.

INTRODUCTION HISTORY AND DISTRIBUTION: Tree of heaven, native to China, was introduced to Europe in 1751 by a Jesuit priest. It was imported into the U.S. in 1784 by William Hamilton, a Philadelphia gardener, and was brought to the west coast by Chinese immigrants for medicinal purposes during the Gold Rush period. This tree was once planted in cities because of its tolerance to smoke and poor soil conditions. It quickly escaped from cultivation on both sides of the country. (18) Tree-of-heaven is widely distributed across the United States today, occurring in forty-two states from Maine to Florida and west to California. Ailanthus is adapted to a wide variety of soil conditions. It tolerates drought and rocky conditions to the extent of growing out of pavement cracks. The tree is common in urban areas and disturbed sites throughout its range, and it is a pioneer in succession with limited ability to compete in a closed-canopy forest. It can, however, take advantage of forests defoliated by insects (e.g., gypsy moth) or impacted by slides, windstorms, or other natural disasters. (17)

IMPACTS ON ECOSYSTEM: Ailanthus forms dense, clonal thickets that displace native species. A few trees along a fencerow or forest edge can rapidly invade adjacent meadows. This tree has become a pest not only by outcompeting native vegetation, but does major damage to roadways, sidewalks, sewer structures and orchards with its extensive root system. (17) In addition to its prolific vegetative reproduction and rooting extent, ailanthus has allelopathic (toxic) effects on many other tree species and may chemically inhibit succession in invaded areas. Allelopathic reactions in over 35 species of hardwoods and 34 species of conifers have been demonstrated for water extracts of ailanthus leaves. (19)

CONTROL EFFORTS: Cutting, spot burning, and foliar herbicide sprays have all been explored but the most effective means of control may be to pull seedlings by hand before the tap root develops. (20) Curtailing the spread of ailanthus in this manner may be impossible, given its prolific reproduction.



	Plants - Tree of Heaven

Home Overview of Invasives Case studies in US forest ecosystems Insects BWA Gypsy moth Plants Tree of heaven Kudzu Pathogens Chestnut blight Dutch elm disease Long-term effects on forests Conclusions References Useful links	*Tree of Heaven (Ailanthus altissima* (Miller) Swingle)** An early Chinese saying refers to spoiled children as "good for nothing ailanthus sprouts." (17) DESCRIPTION: Tree of heaven is a small to medium sized tree in the Quassia family that is a persistent and aggressive weed throughout much of Europe and North America. Its deciduous leaves are odd-pinnately compound with 11-41 leaflets; their shape is lanceolate and each leaflet has a prominent dark green gland on the underside near the apex. Leaflets are each 7.5-12.5 cm (3-5 in) long and 2.5-5.0 cm (1-2 in) wide. Ailanthus reproduces from both seed and root sprouts. Sprouts may emerge up to 15 m (50 ft) from the nearest existing stem. (17) The flowers are unisexual or bisexual and are borne in large terminal clusters in the summer months. One tree can produce up to 350,000 seeds per year; these seeds are easily windblown a great distance and a high percentage of them remain viable. (18) These seeds can germinate in a wide variety of disturbed habitats, including urban and suburban areas and along railroad tracks. This species is known to have a tolerance for polluted environments and poor soils. Ailanthus is moderately tolerant of shade; in natural stands reproduction is primarily by sprouting. The species is relatively resistant to insect predation. (19) The trees are typically short-lived (30-50 years), though some have survived for over 150 years. All parts of the tree, especially the flowers, have a strong, offensive odor when bruised or crushed, which some have likened to peanuts or cashews. INTRODUCTION HISTORY AND DISTRIBUTION: Tree of heaven, native to China, was introduced to Europe in 1751 by a Jesuit priest. It was imported into the U.S. in 1784 by William Hamilton, a Philadelphia gardener, and was brought to the west coast by Chinese immigrants for medicinal purposes during the Gold Rush period. This tree was once planted in cities because of its tolerance to smoke and poor soil conditions. It quickly escaped from cultivation on both sides of the country. (18) Tree-of-heaven is widely distributed across the United States today, occurring in forty-two states from Maine to Florida and west to California. Ailanthus is adapted to a wide variety of soil conditions. It tolerates drought and rocky conditions to the extent of growing out of pavement cracks. The tree is common in urban areas and disturbed sites throughout its range, and it is a pioneer in succession with limited ability to compete in a closed-canopy forest. It can, however, take advantage of forests defoliated by insects (e.g., gypsy moth) or impacted by slides, windstorms, or other natural disasters. (17) IMPACTS ON ECOSYSTEM: Ailanthus forms dense, clonal thickets that displace native species. A few trees along a fencerow or forest edge can rapidly invade adjacent meadows. This tree has become a pest not only by outcompeting native vegetation, but does major damage to roadways, sidewalks, sewer structures and orchards with its extensive root system. (17) In addition to its prolific vegetative reproduction and rooting extent, ailanthus has allelopathic (toxic) effects on many other tree species and may chemically inhibit succession in invaded areas. Allelopathic reactions in over 35 species of hardwoods and 34 species of conifers have been demonstrated for water extracts of ailanthus leaves. (19) CONTROL EFFORTS: Cutting, spot burning, and foliar herbicide sprays have all been explored but the most effective means of control may be to pull seedlings by hand before the tap root develops. (20) Curtailing the spread of ailanthus in this manner may be impossible, given its prolific reproduction.