| Missouri Environment and Garden | Volume 8, No. 5 |
| News for Missouri’s Gardens, Yards and Resources | May 2002 |
Occasionally, extension offices around the state get requests for information about trees described and advertised in the popular press as having near-miraculous characteristics. Royal Paulownia (Paulownia tomentosa, Empress Tree, Princess Tree) definitely falls into this category.
A quick web search turns up about 2500 hits with some type of information on Paulownia tree. Native to China, this member of the family Scrophulariaceae is a tree that may attain an ultimate height of about 40 to 50 feet in our climate if planted on a good planting site. The species was introduced into the United States about 1834 and "escaped" from cultivation soon thereafter. The attribute of Paulownia that tends to attract the most attention is its growth rate. Under ideal conditions, this species can grow up to 15 feet in a single season. This rapid growth rate is both a blessing and a curse in the Midwest. Although it may be possible to grow a 20-foot tree in a few years, the wood is brittle and subject to wind and ice damage. The rank growth habit also makes the tree subject to freezing injury caused by sudden temperature drops in the fall before the plant has hardened off. A tree on the University of Missouri campus never grew taller than ten feet because it froze to the stump each winter until it was removed. Theoretically, this susceptibility to freezing injury can be reduced by obtaining trees grown from northern seed sources. If so, then this species may have some potential as a timber species since the wood is prized in Asia for manufacturing specialty items. There is no demand for the wood in the U.S.
In addition to its rapid growth rate, Paulownia has some ornamental characteristics that attract attention. Its large, tropical looking, heart-shaped leaves create dense shade. If you like to rake leaves, this is the tree for you. Its most head-turning feature, however, is its floral display. With foot-long panicles of vanilla-scented, 2-inch, violet and yellow flowers, this tree is hard to dislike when it blooms in April or May. The round, brownish seed pods that persist into winter are considered by some to be ornamental. Unfortunately, the flower buds are often killed in our climate by low temperatures in winter or spring.
Regardless of its potential for use as an ornamental or timber species, Paulownia has some potential ecological liabilities. In an article describing the species, Tom Remaley, a naturalist with Great Smoky Mountains National Park ( http://www.nps.gov/plants/alien/fact/pato1.htm), points out that the species can spread aggressively on disturbed sites from stump sprouts and root suckers. Also, a single seed pod may contain up to 2000 seeds which can travel some distance on the wind and germinate within a few days on moist soil.
In summary, although our featured miracle tree is truly impressive in growth rate and flowering characteristics, Paulownia has some distinct liabilities in our climate. As Grandma always says, "anything that sounds too good to be true usually is." For a more flattering view of the species than that presented here, see http://www.paulownia.org/.
Chris Starbuck, Woody Ornamental Horticulture, UMC (573) 882-9630