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Bad Trees, Trees Prohibited by Code, Part I

By Buck Abbey, ASLA & Robert Reich School of Landscape Architecture Louisiana State University

The Louisville, Jefferson County, Kentucky code lists 32 species of prohibited plants, many for their "messy fruit": Diospyros, Ginkgo, Gymnocladus, Malus, Moros, Maclura and Pyrus. Gymnocladus, meaning "naked branch," has another problem going for it. Its raw seeds are poisonous. Native Americans, however, used the bark in a concoction to cure constipation.
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"A tree that looks at God all day, and lifts her leafy arms to pray."
Alfred Joyce Kilmer 1886-1918

Tree Regulations
Alfred Joyce Kilmer believed that every tree had merit. We love trees because they provide shade, nurture the environment and adorn our gardens. But we hate them for different reasons. The most common being that trees can be travelers and can end up in places they are not wanted. When they show up, they are often rejected, stigmatized and prohibited!

Unwanted species are labeled "bad trees," members of the plant kingdom's criminal element.

Albuquerque, New Mexico prefers female trees since the male tree is largely responsible for wind-driven pollen counts. The community identified several genera of "bad trees" in its code, including the family Cupressaceae (cypress) and Moraceae (mulberry) as the biggest offenders. The city of Irvine, Calif., on the other hand, loves cypress trees, as witness to the cypress allee in the city hall parking lot.
Photo: LASN Editor Stephen Kelly

Prohibited species are unwanted plants in a community for a number of reasons. Affronts to humankind may be of the tree's own making, or they may be transgressions specifically proscribed by community policy crafted by a local tree broad or landscape commission. But for whatever reason specific characteristics of a tree's inherent nature will often hound them out of town.

Character flaws are generally noted in tree legislation. Flaws capable of banishing a tree may come from several aspects of a plant's character that people react to in a hostile manner. As we will see below, these faults result from growth rate, invasiveness, susceptibility to disease, untidiness, hardiness and harmful effects upon people or property. Some bad trees are simply harbingers of disease, insect pests or pathogens and quickly make the list. But it is the community tree law that impinges the reputation of a tree the most. A community tree ordinance can brand a tree for life as a "no account." It is banned, shunned, rejected, looked down upon and often found facing the chainsaw. Not a nice position for a tree to find itself in.

Miami-Dade County, Fla. identifies species of trees that cannot be planted in the county, including Casuarina (ironwood). The county may not like it, but C. oligodon, is a good building timber and makes excellent firewood. The tree's root nodules are prized for increasing soil fertility and its leaves are prized for mulch (high in nitrogen content). The resin exuded from some casuarinas is edible and was a food source for Aboriginal people.

Making the List
The Louisville, Jefferson County, Kentucky code (chapter 10, "Tree Canopy, Landscaping and Open Spaces," Appendix B) lists 32 species of prohibited plants, many because they bear "messy fruit." Some of the trees have wonderful flowering or fruiting effects, but do not meet code. Some plants on this list are unwanted because they are female plants. The female plants are guilty of having obnoxious fruiting bodies. Examples include Diospyros, Ginkgo, Gymnocladus, Malus, Moros, Maclura and Pyrus.

Albuquerque, New Mexico actually prefer female trees since it is the male tree that is largely responsible for offending wind-driven pollen counts, which is the bane of air quality in this western community. The community identified several genera of Bad Trees in Section 9-12-5 Regulated Trees of the community code. Trees in the family Cupressaceae and Moraceae are the biggest offenders. Restrictions are placed on other trees also, including juniper, cedar, cottonwood, poplar, sycamore, ash and elm. Prohibited trees may not be purchased outside the city and transported within to plant.


by Alfred Joyce Kilmer (1886-1918)

Note: Kilmer was an American journalist, poet, literary critic, lecturer, editor and ... solder. He died in combat during the Second Battle of the Marne at age 31.

I think that I shall never see
A poem lovely as a tree.

A tree whose hungry mouth is prest
Against the earth's sweet flowing breast;

A tree that looks at God all day,
And lifts her leafy arms to pray;

A tree that may in Summer wear
A nest of robins in her hair;

Upon whose bosom snow has lain;
Who intimately lives with rain.

Poems are made by fools like me,
But only God can make a tree.

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May 19, 2019, 8:27 am PDT

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