By Corinne Kennedy

*Paulownia tomentosa*, empress tree, just outside the Seattle Japanese Garden. (photo: Aleks Monk)

Paulownia tomentosa, empress tree, is a fast-growing deciduous tree with a long history in Asian folklore, tradition, and medicine. It flowers in May, before the leaves open, with large clusters of showy, pale purple blooms that resemble those of the herbaceous foxglove plant.

Visitors to the Seattle Japanese Garden pass a tall empress tree as they walk from the parking lot to the Garden’s entrance courtyard. It was planted in 1987 when a rock display and memorial plaque was installed there in honor of James K. Fukuda, the Japanese Consulate’s Cultural Affairs Liaison. Fukuda was bilingual, served as Garden designer Juki Iida’s full-time translator, and was instrumental in facilitating communication and cooperation among the Garden’s Japanese designers and its Japanese American builders.

Paulownia tomentosa is one of several Asian paulownia species (usually said to be between 7 and 17 species, with authorities unable to agree on an exact number). Native to China and Korea, it has naturalized over a wide area in Japan, and some authorities believe that it is native there as well. (Previously assigned to the family Scrophulariaceae, Paulownia has been given its own family, Paulowniaceae.) The genus word, Paulownia, is a reference to the Russian Princess Anna Pavlovna, daughter of Tsar Paul I, and the specific epithet tomentosa (“densely wooly, with matted hairs”) refers to the tree’s fuzzy leaves, notably their undersides. Common names include empress tree, princess tree, royal paulownia, and foxglove tree. In Japan, it is known as kiri.

Flower clusters of *Paulownia tomentosa*. (photo: Aleks Monk)

Empress tree is very fast-growing, with smooth bark, thick shoots, a broadly columnar habit, and a rounded crown. Forty to sixty feet tall at maturity, it is considered one of the fastest-growing trees in the world, and is noted for its profuse spring flowering. Flower buds are formed in autumn, and blooming begins in May, before the leaves expand. The individual flowers, up to two inches long, are tubular, funnel-shaped, and sweetly fragrant, with a vanilla-like scent. Pale purple or pinkish-lavender in color, they have attractive interior markings—dark purple spotting and yellow striping—and are arranged in large, upright panicles, up to 14 inches long, that resemble the flower clusters of foxgloves. Edible, they are sometimes used in salads. Fruits are dry, brown, two-valved capsules, 1-2 inches long. Maturing in late summer, they often persist through winter. Each fruit contains up to 2000 small, winged seeds.

Large bright green leaves, 5-12 inches long, are heart-shaped and pointed at their tips. Unlobed or shallowly 3-lobed, they are held opposite on the stem. The fine hairs on their upper sides are relatively sparse, but their undersides are densely wooly. (Although often described as resembling the leaves of catalpas, the two trees are not related.) They drop in autumn without developing noticeable fall color.

Plant parts of *Paulownia tomentosa*: flower panicles with unopened buds; panicles with opening flowers; individual flowers; leaf; seed heads; and seeds. (botanical drawing: Mihailo Grbic, Wikimedia Commons)

Paulownia tomentosa is hardy to USDA Zone 5 (minimum temperature -20 degrees Fahrenheit), and grows best in full sun, in moist, deep, well-drained soil. However, it tolerates part shade, poor soil, atmospheric pollution, and coastal conditions, and has no serious pest or disease problems. Because of its fast growth, it has weak wood and should be sheltered from wind.

A prolific self-seeder, empress tree has escaped from cultivation in some regions. It has naturalized in the U.S. from southern New York to Georgia—and is considered invasive in southern forests. Though common in our region, it is on the “monitor list” of the Washington State Noxious Weed Control Board, not its noxious weed listing. Local tree expert Arthur Lee Jacobson describes it as “restrained, though the powerful root system makes short work of paving.” It also produces dense shade, making it difficult to grow other plants beneath its canopy.

Paulownia tomentosa takes well to pruning, and can even be treated as a “cut-back shrub.” Some gardeners cut the entire tree back to near ground level each year after the leaves have fallen. The following year, it will grow to about 12 feet tall, with huge leaves, 20 inches long or more. With this treatment, it brings an exotic and jungle-like look to the garden, but doesn’t flower or develop fruit.

Paulownia trees in Asian Culture, Art, and Daily Life:

Various Paulownia species have been cultivated in China for more than 3000 years—for their useful wood, showy flowers, and the medicinal uses of their bark, wood, leaves, flowers, and fruit. It was early recognized that paulownia wood was strong and light, and excellent for making furniture and musical instruments. Among the aristocracy, it was customary to plant a tree at the birth of a daughter, and to harvest its wood for her dowry chests when she was old enough to marry. With the passage of time, this custom made its way to Japan. But despite paulownia’s long history in China’s culture and daily life, it was rarely represented in the country’s art.

Paulownia tomentosa is the only species known in Korea and Japan. (It was also the first species to become known in the West, having been introduced to France from Japan in 1834.) Seattle Japanese Garden Guide Maggie Carr researched the history and cultural uses of empress tree for a 2019 Continuing Education class developed for guides. She notes that in Japan the tree and its wood were highly valued by 200 C.E. The following paragraphs are from her class document:

“Carving the wood of Paulownia is an art form in Japan. It is the lightest wood in Japan, soft and warp-resistant. The wood is used to make musical instruments like the Japanese koto and Korean gayageum zithers, and to make geta (clogs). The wood is burned to make charcoal for sketching and powder for fireworks, the bark is made into a dye, and the leaves are used in vermicide preparations. Its wood cells are very porous which makes it heat and fire resistant so it is used to line safes. Geisha used a treated, dried Paulownia branch to make up their eyebrows…

The soft, lightweight seeds were commonly used as a packing material by Chinese porcelain exporters in the 19th century. Packing cases would often leak or burst open in transit and scatter the seeds along rail tracks, resulting in massive spreading of the tree.

During the Heian period (794-1192) in Japan, the color purple was considered a royal color. Paulownia trees were planted at the Imperial Palace. The Tale of Genji is the centerpiece of Heian literature and Paulownia an abiding presence within the novel…

Emblem of the Prime Minister of Japan, with its image of Paulownia tomentosa. (image: Wikimedia Commons)

The Paulownia Seal originally was the private symbol of the Japanese Imperial Family, from as early as the twelfth century. The Toyotomi clan, who ruled Japan before the Edo period, adopted the Paulownia Seal for use as the crest of his clan. Now it is the seal for the government of Japan and is used in official documents.”

Unlike in China, paulownia trees have often been represented in Japanese art, notably in woodblock prints. The beautiful and evocative woodblock below was created by Hiroshige II, the son-in-law and successor to his famous namesake, as a replacement for the original woodblock (plate 53 of One Hundred Famous Views of Edo), which had been damaged or lost.

Woodblock print, “Paulownia Trees at Akasaka in the Evening Rain 1859.” (image: Utagawa Hiroshige II, Metropolitan Museum of Art, Open Access Initiative)

Empress tree has long been grown for timber in Japan, but despite its cultural and commercial significance there, it’s seldom planted in gardens. With its very rapid growth rate, it quickly outgrows most garden spaces—and is also considered unsuitable for bonsai.

In the U.S., authorities also advise against landscape planting, but in our state, Paulownia tomentosa is not labeled a noxious weed. It’s common in large Seattle landscapes, including the Washington Park Arboretum, the Woodland Park Zoo, the Carl S. English Jr. Botanical Garden at the Locks, and the University of Washington Campus. We can admire and appreciate empress tree in those settings—and at the Seattle Japanese Garden. Before entering our Garden’s special world, we walk under the canopy of this magnificent specimen, so evocative of Japan’s rich culture, traditions, and art.

Corinne Kennedy is a Garden Guide, a frequent contributor to the Seattle Japanese Garden blog, and a retired garden designer.

Empress Tree Blooms in Late Spring with Large, Pale Purple Foxglove-like Flowers

By Corinne Kennedy