Nine native trees that hold leaves in winter

Native broadleaf trees with persistent foliage

Have you noticed that a few broadleaf trees change color in fall, but don't drop their leaves? Many of their brown leaves cling to the tree throughout winter and early spring until new leaf growth begins. This characteristic is called marescence.

Here are nine native trees that behave in this fashion.

• American beech (Fagus grandifolia)
• American hophornbean (Ostrya virginiana) also called ironwood
• Sycamore (Platanus occidentalis) also called American planetree or buttonwood
• Black oak (Quercus velutina)
• Blackjack oak (Quercus marilandica)
• Northern pin oak (Quercus ellipsoidalis)
• Pin oak (Quercus palustris)
• Shingle oak (Quercus imbricaria)
• White oak (Quercus alba)

Perhaps it's no surprise to you that the majority are oaks. Owners of these oak trees often complain that they shed leaves all winter long. I know an elderly lady who is very opposed to oaks as the national tree. She has lived her entire adult life under big white oaks, and she hates the way they drop their leaves a little at a time, all winter. "Just not tidy trees," she told me.

Trees with some winter foliage will perform better as a windbreak, screen, or sound barrier than trees that have dropped all their leaves.

They will also cast more shade in the winter than trees that have dropped their leaves. Sunshine on the house in winter is generally a good thing, so consider that when choosing a planting site for a tree that keeps winter leaves.

Our pin oak on the evening of February 21.

Look at all those leaves!

Image credit: Pin oak leaf drawing by J. R. Stacy of the U.S. Geological Survey.

Three important things to consider when choosing a tree

Questions to ask before selecting a tree

This spring, you want to plant a tree. What things should you consider when choosing the species that you plant? Here are three important considerations.

1. How much space do you have for the tree?

The very first thing you should do is go out in your yard and determine the space you want the tree to occupy. Pound a stake into the ground at the proposed planting site to represent the tree's trunk. Tie a long string to it to represent the longest branches on the tree.

Walk the string all the way around the stake. Can you make a 20-foot circle (using a 10-foot string) without obstructions? Then you have enough room for a tree with a 20-foot crown. Can you make a 100-foot circle (using a 50-foot string)? Then you have enough room for a tree with a 100-foot crown.

Trees can be planted so that their branches intermingle, but for a tree to fully develop the distinctive shape that is typical of its species, it needs at least the space described above.

When you know how much room you have for the tree's crown, a little research will reveal trees that are the right size for the space.

2. What do you want the tree to do?

Do you want the tree to screen a view? How much shade do you want the tree to provide? Do you want the tree to provide wind protection or function as a sound barrier? Do you want it to provide bright color or interesting leaves? Are you interested in attracting wildlife?

Questions like these coupled with a little research will help you identify the best tree for you while eliminating others from the list of trees that you could plant.

3. How much care are you willing to give the tree?

Are you willing to spray your tree faithfully? If not, you should avoid species that are prone to diseases and pests. Will you have the devotion and the water to care for a moisture-loving tree in times of drought?

How do you feel about cleaning up broken branches after storms? Some of the fastest-growing trees have brittle branches that break easily. Do you mind raking leaves? Many trees that provide dense shade have lots of leaves that fall every year.

Is the tree going to send up suckers in your flower beds and the neighbor's yard? Will it seed itself profusely? Will you have the time and energy to keep suckers and seedlings under control?

If you're purchasing your tree from a nursery, the nursery staff should be able to describe any special care requirements or problems that a tree might have. Your local extension office probably has a horticulturist or arborist who can advise you. Your city may have an urban forester who can describe care requirements of the trees you are considering.

In addition, make use of the free resources your public library and the internet offer. Many excellent reference books are available. Many excellent extension service documents about trees are available online.

A single word sums up this entire post: research. Don't buy the first tree you see. Don't base your decision on the little bit of information that is provided on the tree's price tag. Do some research and make an informed choice based on your unique situation.

Weak branches are a problem with silver maples

Don't plant silver maples too close to your house.

During the recent devastating ice storm in Kentucky, we heard tree branches breaking all night, with terrible pops that sounded like gunshots. Limbs hit our roof with tremendous thumps. Daylight revealed an incredible scene of natural destruction in our yard.

The photo below was taken through the living room window the morning after the storm. This photo shows only a portion of the branches that broke from a large silver maple (Acer saccharinum), about 15 feet from the window. We have dents and a puncture in our metal roof as a result of the falling branches.

This big silver maple tree was planted by the original owner of our house in about 1960. At about 50 years of age now, it's in its maturity. It provides a lot of shade, but it's dangerous because its weak, brittle branches break easily. This is the great flaw of silver maples (also known as water maples or soft maples.)

The tree's main trunk ends at about ten feet. It has five long, massive limbs growing upward from the trunk, and each limb has smaller branches, of course. One of those limbs poses an ongoing (and increasing) threat to our house. I'm afraid that we need to completely remove that limb. It will be hard on the tree to lose it, but we don't have much choice.

Two more silver maples are planted too close to our house. They are younger trees, planted about 1980. One of them is even closer to the house than the tree outside our living room window.

I understand what the planter wanted -- afternoon shade -- and he would be happy to know that his trees provide that. However, as years pass, both those trees are going to be major problems. To prevent large branches from falling on the roof, we'll have to remove whole sections of the trees. It's very sad.

Silver maples have their merits. They aren't very fussy about where they're planted. They grow well in urban conditions. They will grow in compacted soil. They tolerate short spells of standing in shallow water. They are a valuable tree for wildlife -- especially in late winter and spring when their buds, blooms, and seeds provide food at a time that other food supplies are limited. They have a small-but-noticable, red blossom in early spring when not much else is blooming. They withstand drought and heat, and of course, they do grow very fast.

Unfortunately, silver maples also have a very undesirable characteristic -- weak branches that break in every ice or wind storm that occurs.

If you are willing to deal with the broken branches, silver maples will serve as a fast-growing, short-term (50 to 100 year) tree. They grow up to 100 feet in height with 100-foot canopies. You should plant them at least 50 feet away from anything that could be damaged by falling limbs. Consider power lines, roads, and driveways, as well as your house and other buildings when you select the planting site.

Take my advice and you won't ever have a story to tell about broken silver maple branches making dents in your roof.

Will these trees survive construction?

Many trees would die from such abuse.

Someone has purchased a couple of acres near a small river a few miles from our home. They are building a beautiful new home in a bend of the road.

In preparation for construction, they hired someone to bulldoze most of the trees and level the site. A few large trees, mostly sycamores (Platinus occidentalis), were left standing. I confess a degree of morbid curiosity about whether the trees will survive.

Fortunately, sycamores tolerate soil compaction, because I am sure that soil was quite compacted after the bulldozer drove back and forth, again and again.

When the soil is compacted, water, air, and nutrients cannot move freely. As a result, the tree may become stunted or weakened, and it may slowly die over a period of years.

I wonder how much of the root system of those trees was destroyed during the bulldozing. With all trees, the roots that are responsible for taking up nutrients and water are located near the surface of the soil and extend well beyond the tree's canopy.

Sycamores have a particularly shallow root system. In my experience, they often have very large roots radiating from the trunk at soil surface. If large roots have been broken, the trees may begin to lean or they may even fall down in a strong wind.

Look how the vehicles and equipment are parked right under the trees near the house (top photo). Construction materials are piled there as well. All these things are totally against the rules when you want to preserve a tree on a construction site. And their new road runs right over the roots of the two big sycamores they saved on one end of the property (photo below.)

I wish the property owners had taken some measures to protect the trees they decided to save. They could have fenced out the critical root area around those trees and protected their most important roots.

Rather than selecting individual trees and bulldozing the rest, the owners could have chosen clumps of trees to preserve. The few trees they saved are singled out now after a lifetime among comrades. They are unaccustomed to standing alone, and they will be more vulnerable to wind and weather distress than they were in the group.

In areas around the house where they couldn't avoid traffic, the owners could have decreased the likelihood of root damage by applying a thick (6 to 8 inch) temporary mulch under the trees. (Obviously, the mulch would have been most effective if they had not bulldozed the site already.)

Ask me in ten years, and I'll tell you how many of the trees are still alive. I'm not placing any bets, one way or the other. I think sycamores stand a better chance of living through this than many other tree species would. They're tough, but they've taken a good bit of abuse here.

(Some may know the sycamore by other names, such as American planetree, buttonwood, or button-ball. )

How to compute a tree's critical root area

Protect tree roots during construction

It's vital to avoid disturbing or compacting soil around a tree that you want to preserve on a building site. The best way to prevent damage to a tree's root system is simply to fence out the critical root area -- that is, the area that contains the bulk of the tree's roots.

How to determine the critical root area:
1. Measure the circumference of the tree's trunk at 4-1/2 feet above the ground.
2. Divide the circumference by π (3.14) to determine the diameter of the tree's trunk.
3. Multiply the inches of trunk diameter by 1.5. (This gives you the critical root radius -- 1.5 feet for each inch of trunk diameter.)
4. Measure the critical root radius in all directions from the tree's trunk and compare the resulting circle to the tree's dripline. The larger of the two is the critical root area that should be protected.

Walking, driving, or piling construction materials within the fence should be absolutely prohibited. In addition, do not spill or allow runoff or buildup of chemicals, fuel, "cement water", sheetrock dust, etc. in the protected area.

Several university extension services have published some excellent information online about protecting trees during construction. These include:

• Preserving Trees in Construction Sites (pdf, 801K, Mississippi State University )
• Protecting Trees from Construction Damage: A Homeowner's Guide (University of Minnesota)
• Construction and Tree Protection (pdf 1.7MB, North Carolina State University)
  

Top 100 Botany Blogs

Interesting list

Christina Laun at Online College Blog has posted a list titled "Top 100 Botany Blogs." This blog, Tree Notes, is included in the Trees section of the list.

I'm familiar with a few of the other blogs in the Top 100 list, and I'm honored that Tree Notes is mentioned on the same page as them!

I hope you'll take an hour or two and visit some of the blogs on the list. Reading about green things is a good pastime for a cold February evening.

Weeping willows damaged by ice

Weak wooded trees with a weak structure

I've written previously in this blog about how I love weeping willow trees and how I planted two of them for sentimental reasons, even though I knew better. (See "Weeping willow, a weak-wooded tree" and "One tree not to plant"

I planted them about a dozen years ago. They grew fast, and they were beautiful for a few years. However, they've created a problem in nearly every episode of extreme weather we've experienced.

The devastating ice storm that hit Kentucky a few days ago was particularly hard on my weeping willows. I expect that we will cut them down and spray any sprouts with Roundup. I've had the experience of owning weeping willows now, and it wasn't nearly as pleasant as I thought it would be. I don't want to repeat it.

The tree in front of them -- the undamaged one -- is a black walnut that was planted at about the same time.

More photos of the ice damage to our trees