Monday, June 21, 2010

Japanese Raison Tree

Hovenia dulcis

A very beautiful, large deciduous tree, reaching up to 60 + feet, with an ascending oval crown. It makes an excellent shade tree. It is native from central to eastern China and long cultivated in Japan.. Some records include: fastest recorded growth rate - 6 feet ( 3.5 feet is more average on ideal sites ); largest on record - 115 x 61 feet with a trunk diameter of 4.3 feet; largest in U.S. - 90 x 52 feet at Morris Arboretum in Philly, PA. Another large tree near Philly grows at Taylor Arboretum at Wallingford. Moderately long-lived, the Japanese Raison Tree can persist as long as 300 years. Hovenia is used to reforestation in sandy soil areas in northern China.
The attractive foliage is hlossy deep blue green above and light green below; turning to brilliant golden-yellow during autumn. The heart-shaped leaves are up to 11 x 6 inches in size. The leafstalks are also very long, reaching a maximum length of 11 inches.The foliage looks somewhat like that of the Balsam Poplar.
The mild scented, white to yellow-green flowers are not very visible but are borne during mid-summer on sprays carried on thick stalks.
The interesting small red fruits are massed in large clusters in September and October. This tree can produce fruits in as early as 3 years with an eventual up to 10 pounds of fruits in a year.. This tree is self fertile. The 'Raisons" are sweet.
The bark is gray-white to grayish-brown, smooth and birch like later becoming gray with narrow, shallow furrows.
The Japanese Raison Tree is very easy to grow on any moist, fertile, well drained soil in full sun. It does not enjoy prolonged droughts, low humidity and hot dry winds. Hardy zones 5 to 8 and tolerates as low as -22 F. This tree is not generally prone to pests or diseases.
Propagation is from half hardened cuttings taken in summer or from seed sown immediately upon ripening. Seeds germinate better if you file the hard seed coat before sowing. The seeds can also be soaked in concentrated sulfuric acid then washed off.

* photos taken on May 16 2010 @ Cylburn Arboretum, Baltimore, MD

* photos taken on July 17 2010 @ Morris Arboretum, Philly, PA

* photos taken on June 23 2013 @ U.S. National Arboretum, DC

* historic archive photo

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