After church one Sunday, a friend asked if I would identify a tree growing on his property. The tree was an ailanthus, more commonly known as the tree-of-heaven.
The tree-of-heaven often is confused with sumacs; however, unlike sumac, the tree-of-heaven has a rank, unpleasant odor.
Its scientific name is Ailanthus altissima, with its generic name of Ailanthus from a Moluccan name meaning "tree-of-heaven," which refers to the height of the tree. The species name altissimo is Latin and means "very tall."
PHOTO COURTESY OF BILL BOWER
The tree-of-heaven is of no special importance as a forest tree and is considered an undesirable.
PHOTO COURTESY OF BILL BOWER
The seeds of the tree of heaven.
The tree, which also bears the common names paradise tree and Chinese sumac, is an immigrant from China that has been extensively planted in the United States' larger cities. In the 1780s, the tree-of-heaven was introduced into Pennsylvania.
The tree is extremely tolerant of adverse city conditions and often is the only tree that will grow on certain sites. The tree-of-heaven has spread from these plantings and now is considered a nuisance in 40 states.
The tree-of-heaven is a fast growing tree, reaching as high as 8 feet in a single year.
The male and female flowers are borne on different trees. Male flowers emit a disagreeable odor, while the female flowers produce a bountiful crop of wind-borne seeds.
The tree-of-heaven aggressively competes with more desirable native trees. It has an extensive system of sprouts that spread just above the ground surface, which is one of the reasons it is very difficult to eradicate once established. Since it grows in disturbed sites, even a crack in a sidewalk will provide an area for a seed to grow.
Finding the best way to get rid of the tree-of-heaven has become a serious problem. Fire doesn't work and chemicals, which are expensive, are not always effective. If the tree is cut down, a sprout of about 12 feet will grow from the stump the following year.
Researchers in Pennsylvania now have found a fungus that will kill the tree. A special hatchet that has been designed to pump fungal spores into trees is being used. It usually takes three blows from the hatchet to deliver the 30 million spores to kill the entire tree, including the sprouts. This is important because the sprouts immediately will begin growing if the top canopy of the tree dies.
Researchers also are getting help from nature itself via a beetle. Ambrosia beetles found near infected stands appear to be carrying the fungus throughout the forests and infecting other tree-of-heaven stands, killing them, too. The theory is that beetles feeding on an infected tree will take the spores to other healthy trees miles away.
Researchers are studying what effect the fungus could have on other trees and plants; however, preliminary studies show only a small percent of plants found near the infected trees were harmed by the fungus.
Now for the other side of the story.
In the bulletin Forest Leaves, which is put out by Penn State Extension, an article by Bill Paxton defends the tree-of-heaven as a good tree species.
In the article, he states that the prize of lepidopterists (one who studies butterflies and moths) is the caterpillar that feeds upon the tree-of-heaven. The prized caterpillar came from China and was established in Philadelphia in the 1860s.
The tree-of-heaven originally was to be used as silk moth food; however, the experiment failed, and the tree soon became valuable because of its stately, graceful and ornamental properties.
The article states that although the tree-of-heaven has many glycosides (a sugar derivative) that can affect other plants, the chemicals help enrich forest soils, enabling other seedlings to grow better; also any harmful effects from the chemicals drop to zero 5 feet from the base of the tree.
Paxton also states that the tree produces at least 10 natural chemical compounds, of which some are used in cancer therapies.
I also read in the article that the tree-of-heaven's dead branches and decaying leaves on the forest floor contain nutrients that are four times higher than any other native tree, which allow the tree to survive and grow faster in poor soils, such as reclaimed areas.
Finally, the article states that it is an important tree and is planted for timber and reforestation in New Zealand, the Middle East, Eastern Europe and South America.
Bill Paxton also mentions that there are many other trees that may be worthy of a "search-and-destroy" mission, such as the ash-leafed maple, white mulberry, Chinese elm and Norway maple to name but a few.
Bower retired after 34 years as a wildlife conservation officer for the state Game Commission. He has published several books about his experiences. Questions and comments may be sent to him at 153 Redington Ave., Troy PA 16947.