Paulownia is a genus of from 6 to 17 species (depending on taxonomic authority) of plants in the monogeneric family Paulowniaceae, related to and sometimes included in the Scrophulariaceae. They are native to much of China, south to northern Laos and Vietnam, and long cultivated elsewhere in eastern Asia, notably in Japan and Korea. They are deciduous trees 12–15 m (40–50 ft) tall, with large leaves 15–40 cm across, arranged in opposite pairs on the stem. The flowers are produced in early spring on panicles 10–30 cm long, with a tubular purple corolla resembling a foxglove flower. The fruit is a dry capsule, containing thousands of minute seeds. The genus, originally Pavlovnia but now usually spelled Paulownia, was named in honour of Queen Anna Pavlovna of The Netherlands (1795–1865), daughter of Tsar Paul I of Russia. It is also called “Princess tree” for the same reason. Paulownia fortunei is a fast-growing tree that is grown commercially for the production of hardwood timber. Paulownia tomentosa is listed as an invasive species in the southeastern United States, having been introduced there as an ornamental tree for its decorative flowers.
It is popular in its native China for reforestation, roadside planting and as an ornamental tree. Books say it grows well in a wide variety of soil types, notably poor ones, and needs a lot of light and usually does not like high water tables. Paulownia timber is a pale whitish coloured wood with a straight grain. Its characteristics of rot resistance and a very high ignition point ensures the timber’s popularity in the world market. Paulownia grown on plantations generally has widely spaced growth rings and is therefore much less valuable. The wood is also important in China, Korea, and Japan for making the soundboards of stringed musical instruments such as the guqin, pipa, koto, and kayagum. Testing by CSIRO in Australia has shown that Paulownia wood is very attractive for wood-boring insects. Paulownia species are also used as food plants by the larvae of some Lepidoptera species including Endoclita excrescens.
Paulownia is known in Japanese as kiri (桐), specifically referring to P. tomentosa; it is also known as the “princess tree”. It was once customary to plant a Paulownia tree when a baby girl was born, and then to make it into a dresser as a wedding present when she gets married. Paulownia is the mon of the office of the Japanese Prime Minister and also serves as the emblem of the cabinet and the government (vis-à-vis the chrysanthemum being the Imperial Seal of Japan). It is one of the suits in hanafuda, associated with the month of December. Japan: An Illustrated Encyclopedia (page 1189; Tokyo: Kodansha, 1993. ISBN 4-06-931098-3) states: Paulownia wood is very light, fine-grained, soft, and warp-resistant and is used for chests, boxes, and clogs (geta). 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.
The fine grained soft and warp resistant properties also make Paulownia wood exceptionally suited for making wooden surfboards. Tom Wegener (Noosa, Australia) and his brother Jon Wegener (California, USA) are amongst the shapers who pioneered its use. Other shapers like Empress Surfboards and Scud Surfboards (France) are also making surfboards out of Paulownia. Unlike those made from balsa wood, the resulting surfboards do not need to be glassed. More recently, it is used as body material for low-cost electric guitars and as the core for lightweight touring skis. It is often used in guitars as the core body, then finished with another kind of wood, such as the Dean ML XM that is made of paulownia as the body but is finished with mahogany.
Paulownia is extremely fast growing; some species of plantation Paulownia can be harvested for saw timber in as little as five years. Once the trees are harvested, they regenerate from their existing root systems, earning them the name of the “Phoenix tree.” Paulownia has the ability to reclaim ecologically stressed and degenerate patches of land relatively quickly. Its root systems run deep and penetrate compacted and contaminated soils which have resulted from industrialized development. Paulownia is a phyto-remediator, increasing the organic content of degraded soils, processing and filtering contaminants through the uptake of its vascular system, and emitting oxygen into the atmosphere.
Recently, Paulownia has received a great deal of interest for its environmental properties and has been put forward as a potential solution to the global deforestation problem which lies at the heart of the climate change debate. It is being used as a reforestation tree in several countries, including Australia, Germany, China, the USA and Panama. Reforestation projects using the species are being run by organizations such as EcoTech Timber Inc, ECO2 Forests Inc, Robinia Invest, Eco Sustainable Systems, Silva Tree and Kiri Park Projects due to Paulownia’s fast growth and additional environmental benefits. Paulownia has also proved to increase food production when used for intercropping and to prevent soil erosion. A large reforestation project in China increased food production in the Yellow River and Yangtse flood plains and halted erosion on approximately 3.15 million ha (12,200 sq mi) of land.