Royal paulownia (Paulownia tomentosa), also known as the royal empress tree, empress tree or princess tree, is one of the fastest-growing trees in the world. It has been used for centuries not only as a landscape tree, but for medicinal and commercial uses as well. Large, tropical leaves and heavy, tubular blooms that cascade in springtime are attractive, but the invasive qualities of this species outweigh the benefits.
Native to China, written descriptions of the royal paulownia date back to the third century B.C. Leaves, fruits, and other parts of the tree were used both medicinally and as beauty treatments; a document from 1049 details the cosmetic uses of the royal paulownia. The tree was much respected in China, Japan and other areas in Asia. Traditionally, parents planted a royal paulownia when a baby daughter was born. When their daughter was old enough to marry, the tree was cut down and made into furniture, dowry chests, or other items. The legendary phoenix would land only on the royal paulownia, and then only during the reign of a righteous emperor. The wood was valued in Asia for its durability, and it was easily carved or formed into musical instruments, furnishings, and other household items. Paulownia lumber is still valued today, and plantations of the fast-growing tree now exist in North America, Australia, and other countries.
Introduction to North America
Introduction to the United States occurred in the 19th century. In the 1800's, the light, springy seeds were used to pack china and delicate goods imported from Asia. The seeds often escaped when cargo opened, and trees sprung up along rail lines and other places along the Eastern seaboard. Around 1840, the tree was deliberately imported as a landscape ornamental by the Dutch East India Company. Many early growers cut down or pollarded the royal paulownia in autumn, like a perennial flower, but this did not prevent the tree from spreading.
Large, heart-shaped leaves and pale lavender-blue flowers hanging in large clusters give the royal paulownia tree a tropical air. The spring flowers appear before the leaves, and mature into seedpods shaped like large acorns or a child's toy top. The leaves themselves are leathery, and the leaf's underside is covered with small hairs. There is no strong taproot. Varieties do exist, but the most commonly seen is Paulownia tomentosa.
The growth rate of the royal paulownia may tempt landscapers. Suckers from existing roots can grow 15 feet in a single growing season, and the mature height can be between 30 to 60 feet. When shade is wanted quickly, a royal paulownia may seem to be a perfect choice. However, the rapid growth will overtake most suburban yards and can result in a weak, easily broken limb structure. This, combined with tough leaves dropping in autumn, surface roots, and numerous seeds, makes the royal paulownia a nuisance. Add the invasive tendencies, and most gardeners will avoid this tree.
The royal paulownia is considered invasive in many states. It is surprisingly tenacious; trees can be cut down seasonally for six or more years before the root system is exhausted, suckers from consumed trees sprout rapidly after forest fires, and even bulldozing a royal paulownia will not prevent this tree from regrowing. This tenacity is valued in the lumber industry; once a tree is cut for sale, a new tree will sprout and rapidly grow from the old stump. Although the royal paulownia can grow from roots and buried branches, the majority of the unwanted plants come from windblown seeds. Twenty million seeds form in the seedpods of a single tree and are carried long distances. The seedlings quickly adapt to most soils and displace native vegetation.