Paulownia elongata, foxglove tree, Kiri seeds
Paulownia elongata belongs to the family of the Paulowniaceae, the foxglove trees. Paulownia elongata is also known as Kiri, empress tree or princess tree. The plant is native to Asia, although one could think that the plant comes from Russia, because the genus is named after a Russian princess. P. elongata is the most abundant species in the genus Paulownia. P. elongata is a fast growing tree. The trunk is quite straight. The Kiri can reach a height of about 20m. In the first 10 year is grows very fast. P. elongata is the fastest growing species of all Paulownia species. Only the Hybrid Paulownia shantong grows faster. P. elongata is resistant to fungies, decay and pathogens. The leaves of the empress tree are bluish green and slightly lobate. The leaf edge is serrate or waved. The bottom side of the leaf is pubescent. The leaves have a long petiole. Paulownia elongata is a popular tree in cities. The Kiri is cultivated in parks and near streets. Due to its big leaves and the hairs on the bottom side it can absorb great amounts of carbon dioxide. That fact makes this tree really interesting for big cities where the air is strongly polluted. In tropical regions P. elognata is evergreen, in temperate regions the leaves get brown in autumn and fall down. The flowers of the empress tree are zygomorphic and hermaphrodite. The color is similar to lavender. Sometime the flowers get dark blue. The center of the flower is yellow. The flowers of the Kiri are clustered in inflorescences. They have a pleasant odor and reach a length of up to 25 cm. That’s one of the reasons why the Kiri is a popular ornamental tree. The fruit is capsule that contains many seeds. The wood of Paulownia elongata is very popular. It is used to build noble furniture for example in yachts. The wood of P. elongata is free of resin. It is comparable to Mahogany wood. Sometimes the wood is also used as energy wood. But it is a pity to burn such a noble wood.
Growing Paulownia from seeds:
The seeds of Paulownia elongata can be stratified but it is not necessary. Stratification can raise germination success. For stratification the seeds in the substrate should be put for some time into the fridge at a temperature of about 4°C. After that they should be placed sunny. The seed should be only covered slightly with substrate, they need light to germinate. At a temperature of about 24°C and constantly moist substrate, germination occurs after 4 to 6 weeks. P. elongata is winterhardy and tolerates temperatures down to minus 20°C. The Kiri grows best on slightly acid soil. A pH of 6,5 works best. The adult plant should be placed sunny. Paulownia elongata can also tolerate shade.
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