Category Archives: Education

❤️ Weed Trees ❤️

Here’s a dictionary definition of a weed: “a wild plant growing where it is not wanted and in competition with cultivated plants.”

That definition leaves out a lot, doesn’t it? You hear the word “weed,” and somewhere in your mind you’re probably thinking “annoying” and “unsightly.”

People talk about “weed trees,” too. They spring up on their own, often in places where other trees may struggle to thrive or even survive. They’re exceedingly common. They may have characteristics that don’t fit the classic image of a tree, e.g., they may be bushy, misshapen, etc. And they’re scrappy: they can out-compete trees that we think of as conventionally beautiful, stately, grand, majestic, noble — all that good stuff.

Boxelder (Acer negundo) comes to mind. It’s a species of maple native to North America. Check out this guy. Talk about scrappy:

Photo credit: Arieh Tal

Here’s its compound leaf with leaflets (7 here but can be as few as 3), to help you identify the tree :

Photo credit: Glen Mittelhauser

Weed tree? Yet entomologist Doug Tallamy says 285 species of Lepidoptera (moths and butterflies) rely upon boxelder to survive their caterpillar stage.

So many bugs! Here’s the secret: boxelder is terrible at doing what many other trees do incredibly well, which is to seal off decay. Which means that boxelder rots. And what loves rotting wood? Bugs!

And birds love bugs, of course. So boxelder indirectly feeds lotsa birds, too.

Can you build a beautiful, long-lasting dining room table out of boxelder wood? Nope. But can you sustain an ecosystem encompassing hundreds or perhaps even thousands of different insect and animal species with boxelder trees? ? Yep.

From Ecology of Center City, Philadelphia by Kenneth D. Frank.

Yes, those are boxelder seedlings, bringing a stone staircase to life. Not bad for a weed.

Memorial Day 2021

In Marietta National Cemetery there lie not quite 19,000 graves of men and women who served their country. One of them is my uncle Robert Northington Hardeman III, known to his family and friends as Bobby.

He died, still a teenager, during the Battle of Saipan (June 15-July 9, 1944) in the Pacific.

Marietta National Cemetery, like many cemeteries, is a tranquil site, where many of the graves are shaded by mature trees.

Those trees are chestnut oak (Quercus montana), which is in the white oak grouping of oak trees.

The leaves of the chestnut oak have many shallow lobes, not unlike the leaf of a chestnut tree.

By the way, you do know how many wonderful trees you can find at Oakland Cemetery, don’t you? About 1,600, in fact. It’s a marvel. I highly recommend a walk there, sometime soon.


It’s that time of the year.

Chinese chestnut (Castanea mollissima)
Spiky flowers of the Chinese chestnut tree, called catkins.

A large Chinese chestnut tree (Castanea mollissima) is in bloom near my house, and it’s once again filling the air with an . . . ammonia smell which is seriously unpleasant.

The culprits are nitrogen-containing volatile organic compounds (VOCs) which include (for you chemists out there) 1-pyrroline, 1-piperideine, 2-pyrrolidone, and phenethylamine.

Chemical structure of 1-pyrroline

What’s the deal? Presumably the tree evolved this smell to attract pollinators. A recent scientific study of Castanea mollissima in China identified the chestnut’s pollinators as flies.

Those researchers suggest that we should add Chinese chestnut to the list of plants that rely upon sapromyophily for a reproduction strategy.

That is, this tree emits a smell that deceives carrion flies into believing that they’re visiting rotting flesh.


Naturally, I cannot help but imagine what it must have been like to be out in the forest when the mighty American chestnut (Castanea dentata), erstwhile queen of the mountainous forests in the eastern U.S., was in bloom.

And, hey, I’d happily cope with a couple of weeks of that yucky odor to have those trees back, safe and sound from the chestnut blight.


The next time you’re in the Poplar Circle area of Freedom Park, pause to admire this beauty.

Katsura (Cercidiphyllum japonicum)

Katsuratree comes to us from Asia — Japan and China to be precise — and we have this gentlemen to thank:

Thomas Hogg, Jr. (1819-1892)

Beginning in 1862, Thomas Hogg, Jr. was stationed at a new U.S. consulate at Kanagawa, south of Tokyo. The man knew plants. His father, an emigrant from Scotland to New York City, had operated a nursery on the site of today’s Madison Square Park (Broadway and 23rd) in Manhattan. Thomas’s brother James took over the business after their father died.

Immediately upon arriving in Japan, Thomas Hogg started sending home seeds of plants entirely new to North America. In the 1870s, he made a second trip to Japan and continued his collecting.

Everything from our wonderful Japanese maples to our evil, evil kudzu vines can be traced back to the industrious Mr. Hogg.

Inman Park is simply full of Hogg’s legacy, good and bad: fragrant snowbell, Japanese snowbell, Kousa dogwood, varieties of camellia, ‘Limelight’ hydrangea, oriental bittersweet, Japanese knotweed, and more.

He was justly proud of having introduced the katsura to these shores. Its botanical name is Cercidiphyllum japonicum (because its heart-shaped leaf is similar in shape to our redbuds, the genus of which is Cercis).

Katsura leaves (note the reddish color of new leaves)

In its natural habitat, katsura can grow quite large and live a long time. A man named Charles Sprague Sargent, who was the first director of Harvard’s Arnold Arboretum, had a photo taken of this tree on his trip to Japan in 1892. See how older katsuras tend to develop multiple trunks:

In fact, there’s a katsura on the grounds of the Arnold Arboretum with just such multiple trunks. This tree was grown from seed collected by another 19th-century botanist, a man named William S. Clark, during his 1876 expedition to Japan:

Arnold Arboretum katsura

There’s lots to love about katsura. Check out this fall foliage:

Katsura in autumn

Also in fall, the leaves emit a smell similar to caramel or cotton-candy, though not everyone can smell it. It’s generated by a chemical compound called maltol, which is also emitted by such items as bread, warmed butter, chicory, and cocoa.

Tale of An Oak Tree

When Jeanne and I moved into our Waverly Way home, back in the year 2000, there stood a huge water oak (Quercus nigra) between our house and our neighbor to the east.

Several years later, that oak died, and so our neighbor had to take it down. But it left some acorns behind!

In 2010, you can just see a sapling poking its head out of the bushes, in front of the flowering dogwood:

The next year, it’s making a bit of progress, though it’s hard to pick it out among all the other volunteers.

By 2014, with its root system just the way it wants it, the oak has leapt up.

Here is the tree now, on May 22, 2021. Roughly a decade of growth. It’s more than 60 feet tall. Look to the left. That’s a white oak (Quercus alba) that I myself planted probably five years before that water oak even thought about germinating.

Sixty feet tall in 10-12 years!

Sign the Inman Park Leaf Blower Petition

Gas-Powered Leaf Blowers in Inman Park

Residents of Inman Park in Atlanta, Georgia, should voluntarily restrict their use of gas-powered leaf blowers (GLB) to the following times and days: 10:00 a.m. to 4:00 p.m. from Monday to Friday, noon to 4:00 p.m. on Saturday, and not at all on Sunday.

Noise from GLBs is a source of unhappiness and inconvenience for many Inman Park residents. More than that, GLB noise can damage human health as well. The CDC, the EPA, and OSHA all identify leaf blowers as a source of harmful noise. Among the people most at risk are those who work from home, people who work night shifts, children, the retired, the elderly, the sick, and of course the landscape crew itself.

It's not just humans. A scientific study in 2018 found that the noise we humans generate affects wildlife, too. It alters stress hormones in birds, for example. One consequence is that chicks nearer to noise tend to be smaller, with poorer feather development.

Other negative effects of GLBs are well documented, especially with regard to air pollution. You could drive your car, with its efficient pollution-control technology, all the way to California, and you still wouldn't come close to producing the same amount of certain pollutants as GLBs create in the course of an ordinary day of leaf-blowing in Inman Park.

Alternatives to GLBs exist. A battery-powered blower is one example. More and more yard maintenance companies are going all-electric, including in Atlanta. Moreover, hundreds of cities and towns have already adopted restrictions on the use of GLBs.

By signing this petition, you are pledging to limit your GLB use (if any) to the specified days and hours, and you are encouraging others to abide by these modest, voluntary restrictions as well.

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Our TPO Recommendation For Inman Park

On May 17, 2021, the Atlanta City Council is scheduled to vote on a thoroughly rewritten and expanded Tree Protection Ordinance (TPO).

Tree Watch recommends that the Inman Park Neighborhood Association support this proposed revision, while encouraging the City Council to work with the Department of City Planning to accept a handful of final changes drafted by Trees Atlanta, or in the alternative, make a persuasive case to the public why these suggested changes cannot or should not be adopted.

The reason Tree Watch recommends this support for the new TPO is that it appears highly likely that it will preserve more trees than the current ordinance, better protect the trees that it does preserve, and increase the quality and quantity of tree plantings.

This conclusion is based on conversations with our longtime partner Trees Atlanta, on materials provided by City Planning, and on what Tree Watch Chair Jim Abbot learned while participating in the multiyear planning process formerly known as the Urban Ecology Framework.

Trees Atlanta has done a thorough analysis of the proposed new TPO and come up with some modest but important improvements. We’ve reviewed all 23 standards and amendments, which Trees Atlanta has already forwarded to the City Council. Tree Watch supports them all.

Certain of Trees Atlanta’s recommendations do appear to be more significant than others, and it is these that Tree Watch suggests IPNA focus on:

Improve the TPO’s Overall Goal: The goal to “protect, maintain, and advance a high-quality urban forest within the boundaries of the City and reverse canopy loss over time” is unacceptably nebulous and weakens the current goal of “no net loss” of trees. Tree Watch recommends a measurable goal of increasing and maintaining our tree canopy to 50%.

Expand the Category of Priority Trees and Improve the Protections Afforded Them: A major change in the new TPO is to differentiate between higher and lower quality trees, with corresponding implications for incentives and penalties. The City Council should insist on a more expansive definition of priority trees, e.g., by reducing the size threshold. Also, additional steps should be taken to strengthen the protection of these priority trees, e.g., by calculating replacement at 100% (not 75%) of the trunk diameter, by exempting priority trees from the homeowner allowance for periodic removal, and by restoring appeal rights for priority trees to anyone in the NPU.

Use the Tree Trust Fund for Trees: Over time Atlanta has expanded the permissible uses of the Tree Trust Fund, notably for the acquisition of forested land (good) and as budget-relief for administrative costs, primarily salaries (not good). Moreover, an October 2020 audit by the City, following an investigation by Tree Next Door advocates, found that the departments of City Planning and Parks and Recreation had been misusing the Tree Trust Fund for years. The fund should be used chiefly for the preservation and replanting of trees. Accordingly, stricter limits should be put on the use of the Tree Trust Fund for salaries and other administrative expenses, and the City should commit to a very high level of transparency regarding the fund.

Recommit to Robust Public Participation: On the argument that it will improve efficiency, the new TPO would pare back required postings of tree removals as well as public appeals of arborists’ decisions. It does this, among other ways, by eliminating those yellow signs for early stages of the process, by reducing the amount of time between posting and deadline for appeals, and in some situations eliminating appeals altogether or limiting them to adjoining property owners. The City Council should ask the Department of City Planning to walk back all or some of these changes, using Trees Atlanta’s detailed recommendations as its guide. Why? Because we’ve had 50 years to observe the crucial role the general public can play in environmental protection, and we know it works.

Trees Atlanta has a number of other excellent recommendations on such items as (1) an incentive for reduction of impervious surface, (2) a slightly higher target for site density of trees, (3) getting the most of those so-called pre-application meetings, (4) better tree protection fencing, (5) distinguishing multi-unit housing and institutional projects from commercial projects, (6) parking lot trees, and more.

To read the proposed ordinance and related materials, visit the Department of City Planning website.

To view slides from Trees Atlanta’s four-part webinar evaluating the proposed TPO, click here.

Tree Preservation and Protection in Atlanta

(Remarks delivered at the March 2021 meeting of the Inman Park Neighborhood Association.)

Atlanta’s current tree protection ordinance (TPO) is two decades old. When it was new, it was considered the most progressive in the country. In Atlanta, trees are regarded as similar to air and water. They’re a kind of common-pool resource considered essential to public health and welfare.

The key principles of tree protection in Atlanta are: (1) owners of private property must preserve their trees, with exceptions relating primarily to tree size and construction; (2) anyone permitted to remove a healthy tree in order to build on a lot must, in the typical situation, replant it or pay the City “recompense” to have it replanted; and (3) the public has a formal role to play in the regulatory process, through a citizen commission empowered to hear appeals from the decisions of city officials.

Over time, despite updates to a few sections, the TPO has become less and less effective at preventing unnecessary and unwise destruction of trees. There are several reasons, of which I will mention only three: (1) the formula that puts a dollar value on trees has not kept pace with the times, with the result that trees are dramatically undervalued in comparison to the ecosystem services that they provide; (2) the law is based on science that is seriously out of date; and (3) enforcement of the law has not been equal to the brisk pace of intown development over the past two decades.

Now, after a two-year planning process (which had its ups and downs), the Department of City Planning has delivered to the City Council a thoroughly rewritten TPO. It’s thought that the council will vote on it this spring. So, for me, there are two questions:

  • Is this a better ordinance than the one that is in effect now?
  • Is there a realistic chance even at this late date of strengthening the City Planning proposal to preserve even more trees?

Reasonable people will disagree on the answers to these two questions.

For what it’s worth, I say, yes, City Planning’s proposal will likely save more trees.

As for making this proposed ordinance more stringent with respect to tree preservation, it’s important to note that the proposal is no longer the sole project of city planners in conversation with various stakeholders. It’s now situated within a political process.

It seems to me that developers might well succeed in pressuring the City Council to ease some of the provisions in this proposal. Moreover, there are councilpersons who have already indicated that they are leery of an overly restrictive law, fearing that investment in their districts, like the investment from which Inman Park has benefited, might be stymied by too much regulation.

In short, the City Council is now at the epicenter of what is sure to be a storm of objections, appeals, advice, and so on, coming from every direction. That’s the reality.

Now, there are many, many new provisions and mechanisms in City Planning’s proposal, so many that anyone who claims to know the exact impact that the new law will have on our tree canopy is either overly sanguine or not being forthright.

Fortunately, Trees Atlanta is undertaking to have the draft TPO assessed by experts who can conduct real-world tests of its effects on actual parcels. That will undoubtedly result in some concrete, practical, and credible suggestions for the City Council to consider.

The Department of City Planning has done some modeling, too, which it has already provided to the council. Whether their examples are truly illustrative of how the new law would work, over time and throughout the city, is hard to say. In any case:

  • On a selected commercial lot, the developer’s recompense payment for trees destroyed would have doubled to $24,000 under this proposal.
  • On one residential lot undergoing construction, three of four so-called priority trees would have been preserved while recompense would have tripled.
  • In a second example — an R3 parcel where the current law allowed the property owner to destroy almost every tree — the new law would have saved all but 2-4 of 18 priority trees, and recompense would have more than doubled.

We could spend forever going through the pluses and minuses of this new tree protection ordinance. I do see at least a couple of openings for highly impactful improvements to the draft TPO, and this list could certainly be lengthened, albeit possibly at the risk of diminishing the focus on the merits of each requested change :

  • Keep the overall goal as no net loss of trees, or maybe set a goal of increasing tree canopy to 50%, instead of adopting the wishy-washy objective of “revers[ing] tree loss over time,” as proposed by City Planning;
  • Expand the definition of a “priority” tree, e.g., by lowering the size threshold, since so much in this new law would hinge on the higher protection afforded to that subset of trees.

To conclude, I believe it’s prudent for everyone who loves and values our trees to recognize that this proposed new ordinance will affect everyone in Atlanta: anyone who breathes air, anyone who drinks water, anyone who has even a single tree on her property, anyone who relies upon a healthy economy to have a job, anyone who uses our parks, and so on.

Let’s don’t allow this opportunity to adopt a better ordinance pass us by. My personal recommendation is that Inman Park focus its attention on the top handful of final changes that could improve this draft, and then plan to move forward together with the rest of Atlanta once the new law is in place, understanding that the City can and should make adjustments as needed over time.

To sign up for a webinar on the proposed TPO, visit the Trees Atlanta website.