Japanese Emperor Oak, Daimio Oak
 

Mature Size, Growth, Longevity

Grows 40-65' tall, and 40' wide. Has grown to 80'. Moderate growth rate. Generally long-lived, up to 300 years.

Native Range

Native to Korea, Japan and China. Grows on sunny slopes in thickets in lowlands and mountains in Japan.

Flower and Fruit Details

Flowers are monoecious, wind-pollinated, creamy-tan catkins in April, not showy. Emerge and bloom along with the unfolding of the new leaves in spring. A small acorn fruit, Sept-Nov, inside an interesting cap that is frilly, lustrous, burnished copper colored. Acorns have been long-used in Korean cuisine. Also crushed and used to thicken soups, make cereal & breads, only after removing bitter tannins.

Leaf and Bark Features

Deciduous: Huge, 12" by 7", obovate, shallowly-lobed leaves, actually one of the largest of the oaks. Holds the browned leaves into the winter. Leaves are used by the Japanese as wrappings for Kashiwa-mochi rice cakes for May 5 Children's Day. Fall color is occasionally shades of red, orange, yellow or purple, but may not be showy, depending on genetics of the seed it was grown from. Rough bark, somewhat resembling bur oak as it ages. Tannin is obtained from the bark

Culture and Care

Needs full sun to light shade. Tolerates pH 5.1-7.5, preferring moist, acid to neutral soils. Does well in clay soils. Wind-tolerant. Plant in permanent location. Zones 4(5)-8. No serious insect or disease problems. Possible problems include galls, anthracnose, oak leaf blister, cankers, leaf spots, powdery mildew, borers, scale & lacebugs.

Strengths, Weaknesses, Other Facts

Crushed seeds have been used as a soup thickener and for mixing into cereals and breads. Good wildlife value. 3-season interest: Spring, summer and fall. Rarely seen; occasionally grown in botanical gardens. Also sold as Quercus daimio. Galls that form on the tree are highly astringent, and are used in certain medicines.

Suggested Uses

Makes a good shade tree. Browned leaves persist through winter, so could serve as a screening plant, even in the winter.

Taxa and Plants of this Species at BCA