Dr. Grow: Seeking the favorite shade tree

In my last column I told you about three of my favorite shade trees, willow oak, northern red oak and sugar maple. I also indicated that I would tell you about some more of my favorites in this column. So here goes.About 20 to 40 years ago, everyone was planting sweetgum, Liquidambar styraciflua. You find several of these trees planted in homes that were built within that time frame.

Sweetgum is a pyramidal shaped tree that turns a gorgeous crimson red in the fall. It seems to do well in urban situations, adapting to most soil conditions and withstanding lots of air pollution. Unfortunately this tree has one major drawback. It is a prolific fruit producer.

The sweetgum ball is actually a combination of several dehiscent capsules. If you have ever walked barefoot in yard that has a sweetgum in it, you'll know what I'm talking about. Not only is this fruit a pain producer, it is also a nuisance in the fall. They are hard to rake out of your lawn.

Needless to say, when homeowners found out about the drawbacks of sweetgum, it lost favor rapidly. Very few of them are being planted today.

Now thanks to the wonders of modem science, horticulturists have produced a fruitless sweetgum, Liquidambar styraciflua 'Rotundiloba.' This grafted cultivar of sweetgum has the interesting characteristic of being sterile. Therefore it produces no sweetgum balls or fruit. Not only does it maintain the same fall color as the species, but it has the same growth rate and shape. You can see why this new sweetgum cultivar is one of my favorites.

Another favorite is the old time, tried and true, tulip poplar, Driodendron tulipifera. This tree gets its name from the blooms that resemble tulips. Also known as yellow poplar, this tree grows rapidly, is usually tall and straight, and has a pyramidal form. It provides a lot of shade fairly quickly. The fall color is a very pleasing, golden yellow.

The only drawback that I know of with tulip poplar is that it sometimes suffers from an infestation of scale. Scale is an insect that forms a roof, or scale over itself, and then sucks juices out of the twigs of the tulip poplar. Excess tree sap forms a sticky layer on the twigs, and quite often turns black when algae and bacteria grow in it. Fortunately this insect problem can be controlled with a dormant oil application annually.

My final shade tree favorite is red maple, Acer rubrum. Red maple, contrary to its name, has green leaves in the summer. It grows much faster than a sugar maple. Although it produces fruit called a double-winged samara (kids call them helicopters), they do not pose a cleanup problem.

My students often mistake red maple for silver maple, a soft maple that grows extremely rapidly, but has a tendency to break up during high winds. Red maple wood is much less brittle than that of silver maple, so wind has little affect on it.

The characteristic of red maple that really draws my attention is its fall color. Seedling red maples turn a beautiful yellow gold to red orange to crimson red in the fall. If you want to make sure of the fall color, go to your local nurseryman, and purchase a named variety of red maple. For example, the cultivar Red Sunset will produce an annual crimson red show of color that can't be beat. October Glory develops an orangish shade of red.

I have written about some of my favorite shade trees and explained why they are my favorites. If you have a favorite shade tree, let me know. I also want to know why you like it so much. Perhaps I will agree with you and add it to my list of favorite shade trees.