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Index : Landscape Plants
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- 50. Sapphire Dragon Tree - Top
- I have received numerous inquiries during the past few months about a new variety of tree being sold at retail garden centers here in Tucson. It's also available by mail through several internet sites. It's exotic sounding name is the sapphire dragon tree'.
I knew nothing about this tree in the beginning. Looking through my reference books on plants, landscaping, horticulture, and botany I could find no such plant listed. But though information supplied by retailers of this tree I came up with it's real name: Paulownia kawakamii.
Paulownia is a group of deciduous flowering trees, the most well known of which is the Empress tree, Paulownia tomentosa. From my days in Florida, I remember it as an ornamental tree grown and naturalized in the southeastern U.S., particularly north Florida, Alabama, Georgia and the Carolinas. As a landscape tree it was valued for it's showy violet, trumpet shaped flower clusters and unusually large heart-shaped leaves.
Paulownia kawakamii, the sapphire dragon tree is similar to tomentosa in flower color, leaf size (one foot across), and fast growth rate. According to advertisements, the sapphire dragon tree can reach a height of 10 feet the first year, 15 feet the second, and 25 feet the third. As you can imagine, this fast growth rate makes the tree ideal for timber production. Paulownia tree plantations are located throughout Asia, South America, and even in the United States.
The sapphire dragon tree and other Paulownias are well suited for bio-mass production, but as a landscape tree it may be less than ideal.
To maintain a dense canopy of leaves for shade, it is recommended that the tree be heavily pruned every year or every other year. If allowed to grow naturally, the tree will become rather leggy,' with wide-spaced branches and thin foliage. Moisture loss through large leaves is significant, requiring frequent watering during the growing season.
Although it is unknown how the sapphire dragon tree responds to our desert conditions, an indication may come by looking at the environment where the tree is native; China, Japan, and Taiwan.
In Taiwan, annual rainfall is abundant, exceeding 40 inches annually. The climate is maritime, and the air is moist throughout the year. Although sub-tropical with warm summers, those temperatures seldom exceed 95 degrees F. Winters are mild, with temperatures rarely lower than 40 degrees F. Contrast this with Tucson; well you know the story, it's a dry heat, for much of the year.
Another cause for concern with the dragon tree is it's requirement of deep, well drained, acid soils; this according to researchers at the Virginia Tech Department of Forestry. They also state that the tree does poorest on heavy clay compacted soils, which we have an abundance of in Tucson. A requirement for acid soils may, in itself, eliminate the tree from consideration for planting here. Our soils are very alkaline. Try growing an acid loving gardenia and you'll find it nearly impossible to keep it green and growing, let alone producing flowers.
If this sounds like less than a glowing endorsement of the sapphire dragon tree, your right! The requirements this tree needs to successfully grow are all the ones we don't have in Tucson. I know lots of people that bring plants from "back home" and try nursing them along for a year or so before they finally die. But look at all the wasted time, money and effort.
Our unique and challenging desert environment calls for trees that are up to the challenge. These are the "tried and true" native and desert adapted palo verdes, mesquites, and acacias, among others. I doubt that the sapphire dragon tree has what it takes to join this rather exclusive list.
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Written by John Begeman, College of Agriculture and Life Sciences, the University of Arizona, 520-626-5161.
Material originally appeared in Arizona Daily Star gardening column, on January 18, 1998
- Updated: January 18, 1998
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