Ask An Arborist: November 12, 2009

Tree Identification

Image 1 Submitted by James Image 2 Submitted by James

James from Alpharetta Writes...

"We spent last weekend in a cabin at Fort Mountain State Park in Chatsworth , GA. From the deck we could see a tree with very large leaves. Can you identify it for us? I attached a couple of pictures. Also, can you recommend a good book to identify trees..."

And The Answer Is...

The tree that you spotted with its enormous, opposite leaves and the upright stalks of seed pods is the Princess Tree, aka the Royal Paulownia or Empress Tree (Paulownia tomentosa). This fast-growing tree from Asia reaches a mature height of 40-60 feet tall and 30-40 feet wide. In March, the still leafless tree produces large (24-36 inch) upright stalks of tubular lavender flowers that resemble foxgloves as shown below:

Unfortunately, this tree has some major flaws. It is terribly invasive and a mature tree can produce between 20,000-100,000 seeds per season. I have seen seedlings growing in the cracks of roads, out of weathered walls and even between the cracks in a freeway overpass. Its fast growth and large foliage shade the ground preventing the growth of other desirable vegetation. In natural areas, especially in the Appalachians, it has begun to disturb sensitive habitats home to rare native plants. In short, it's a weed. The paulownia is also a tree with weak structure. Younger trees have hollow trunks and hollow limbs can be found in older trees. This makes the tree less structurally sound and prone to breakage. The wood is used for various ornamental purposes.

The paulownia is often featured in printed magazine and newspaper ads showing a drawing (never a picture) of a fast-growing, lavender-blooming tree. I have a low opinion of those who promote and sell this tree either because they don't know or don't care about the environmental damage they are causing.

Interestingly, we have a native tree that is VERY similar in appearance to the paulownia. The Southern Catalpa (Catalpa bignonioides) grows just as quickly, has large opposite leaves and produces stalks of tubular lavender flowers in May (versus March). Southerners often refer to this tree as "catalba" or "catalba worm tree" because of the caterpillars that defoliate it. These caterpillars are prized as bait by many fisherman and they usually cause the tree no permanent harm. Catalpa trees, like the paulownia, don't have an attractive overall shape and are also somewhat brittle.

Catalpa flowers Catalpa habit

I'm often challenged when I open up my portable folding soapbox to discuss the evils of invasive species, particularly non-native invasive plants. Most people and even many professionals wonder what's the big deal. If you would like to learn more, please read this article that I wrote in 2008.

For more information on the Paulownia tree, you may want to read these articles:

National Park Service: Plant Conservation Alliance
Southeast Exotic Pest Plant Council
USDA: Invasive Plants of the Eastern United States

Finally, to answer James' second question on books for identification, there are quite a few. I particularly like "Trees of Georgia and Adjacent States" with its bounty of pictures and descriptions.

If you are concerned about the trees in your landscape, you can contact a Certified Arborist or a professional tree company in your area through the web site of the Georgia Arborist Association.

If you have comments or questions about this article or want to submit a question that may be used in a future article, please email me.

Unless otherwise noted, Images & Drawings Copyrighted © 2009 by Theresa Schrum - All rights reserved