A Royal Procession in Maryland

Contact: Rachel Cliche, US Fish and Wildlife Service | Rachel_Cliche@fws.gov | 410-639-2108 (ext. 222)

A Royal Procession in Maryland
Paulownia flowers in May. Photo: K. L. Kyde

ANNAPOLIS, MD (May 1, 2007) – Princess tree (Paulownia tomentosa), also known as royal Paulownia or empress tree, is an aggressive ornamental tree that grows rapidly along roadsides, stream banks, forests and rocky slopes. Its ability to sprout prolifically from adventitious buds on stems and roots allow it to survive fire, cutting, and bulldozing. It is, therefore, a very difficult and costly invasive plant to control. This invasive tree originates from China, and is displacing native species in Maryland, possibly impacting rare and threatened species. Princess tree may claim royalty, but its unchecked spread is not welcome in Maryland, and it has been chosen as MISC’s May Invader of the Month.

Princess tree is part of the figwort family and can reach 30 to 60 feet in height. The trunk has rough, grey-brown bark interspersed with shiny smooth areas. The large oval- to heart-shaped leaves are pale green and are hairy underneath, situated in pairs along the stem, although in young saplings they may occur in whorls of three. Princess tree displays showy, pale violet, fragrant flowers in the spring before the leaves appear. The dry brown fruit capsules, which can hold as many as 2000 seeds each, mature in autumn and remain attached all winter, providing a useful identification aid.

Paulownia is found throughout the eastern United States from Maine to Florida and west to Texas, preferring USDA hardiness zones 7-10. This invasive tree tolerates infertile and acid soils and drought conditions, and has been used successfully for surface mine reclamation. It readily invades disturbed habitats such as burned areas, forests defoliated by pests and landslides. It colonizes rocky cliffs and riparian zones and will rapidly take over forest edges and roadsides.

Princess tree was first imported to Europe from China in the 1830’s and brought into the United States as an ornamental and landscape tree around 1840.Paulownia is known for its medicinal, ornamental and timber uses. It is highly prized in Japan and China, where the easily worked wood is used to build furniture and dowry boxes. It is cultivated in the United States and shipped overseas in the form of logs, for top timber prices.

Princess tree reproduces from seed, root sprouts and adventitious buds. A single tree is capable of producing an estimated 20 million seeds that are easily transported by wind and water. Seedlings grow quickly and flower within 8-10 years. This rapid growth and adaptability provides this tree with a competitive edge over native species in Maryland. Extensive colonies of princess trees have degraded native forest and riparian ecosystems, and its management difficulties make it a formidable enemy.

Not planting princess tree and educating others about its invasive nature is one of the most important steps toward control. Native alternatives include serviceberry, redbud, flowering dogwood, sourwood and sweet bay magnolia. Planting native species maintains the natural balance of ecosystems and preserves Maryland’s heritage.

Pautom seed capsules 5 9 06 S
Empty seed capsules remain on the tree through the winter
Brighton Dam grove in bloom 5 11 06 S
Mature Paulownia tomentosa grove

Photos: K. L Kyde

Once princess tree is established, it can be controlled using a variety of mechanical and chemical management techniques. Young seedlings can be hand pulled as soon as they are large enough to grasp. It is important to remove the entire root since broken fragments will re-sprout. Trees can be cut at ground level, but since Princess tree spreads by suckering, repeated cutting of re-sprouts or an herbicidal treatment may be necessary.

Large thickets of Paulownia seedlings can be treated by applying a 2% solution of either glyphosate or triclopyr to the foliage. If it is a full-grown tree or other desirable vegetation present, then applying herbicides to freshly cut stumps can be used as long as the ground is not frozen. Cover the outer 20% of the stump with a 25% solution of glyphosate or 50% solution of triclopyr. Basal bark applications can also be used anytime of the year, as long as the ground is not frozen. Thoroughly apply a mixture of 25% triclopyr with 75% horticultural oil to the base of the tree trunk 12 to 15 inches from the ground. A 50% solution of either glyphosate or triclopyr can also be applied to 3 inch cuts hacked around the trunk of the tree between 6-18 inches above the ground. It is important that each cut goes well into or below the cambium layer.

For more information about other Invasive Species of Concern, visit the Maryland Invasive Species Council.

For more information on the Internet:

Princesstree, Paulownia. James H. Miller (2003)

Invasive Plant Atlas of the United States