''Quercus glauca'' ( syn. ''Cyclobalanopsis glauca''), commonly called ring-cupped oak or Japanese blue oak, is a tree in the beech family (

Fagaceae The Fagaceae (; ) are a family of flowering plants that includes beeches, chestnuts and oaks, and comprises eight genera with around 1,000 or more species. Fagaceae in temperate regions are mostly deciduous, whereas in the tropics, many species ...

). It is native to eastern and southern

Asia Asia ( , ) is the largest continent in the world by both land area and population. It covers an area of more than 44 million square kilometres, about 30% of Earth's total land area and 8% of Earth's total surface area. The continent, which ...

, where it is found in Afghanistan, Bhutan, China, northern and eastern India, southern Japan, Kashmir, Korea, Myanmar, Nepal, and Vietnam. It is placed in subgenus ''Cerris'', section ''Cyclobalanopsis''.

Description

''Quercus glauca'' is a small to medium-sized

evergreen In botany, an evergreen is a plant which has Leaf, foliage that remains green and functional throughout the year. This contrasts with deciduous plants, which lose their foliage completely during the winter or dry season. Consisting of many diffe ...

broadleaf

tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, e.g., including only woody plants with secondary growth, only ...

growing to 15–20 m tall. The

leaves A leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, ...

are a distinct deep purple-crimson on new growth, soon turning glossy green above, glaucous blue-green below, 60–13 mm long and 20–50 mm broad, with a serrated margin. The

flower Flowers, also known as blooms and blossoms, are the reproductive structures of flowering plants ( angiosperms). Typically, they are structured in four circular levels, called whorls, around the end of a stalk. These whorls include: calyx, m ...

s are

catkin A catkin or ament is a slim, cylindrical flower cluster (a spike), with inconspicuous or no petals, usually wind- pollinated ( anemophilous) but sometimes insect-pollinated (as in '' Salix''). It contains many, usually unisexual flowers, arra ...

s, and the

fruit In botany, a fruit is the seed-bearing structure in flowering plants (angiosperms) that is formed from the ovary after flowering. Fruits are the means by which angiosperms disseminate their seeds. Edible fruits in particular have long propaga ...

are

acorn The acorn is the nut (fruit), nut of the oaks and their close relatives (genera ''Quercus'', ''Notholithocarpus'' and ''Lithocarpus'', in the family Fagaceae). It usually contains a seedling surrounded by two cotyledons (seedling leaves), en ...

s 1–1.6 cm long, with series of concentric rings on the outside of the acorn cup (it is in the " ring-cupped oak" sub-genus).

Cultivation and uses

It is planted as an

ornamental tree Ornamental plants or ''garden plants'' are plants that are primarily grown for their beauty but also for qualities such as scent or how they shape physical space. Many flowering plants and garden varieties tend to be specially bred cultivars th ...

in regions of

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

and

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

with mild winters. Its acorns are edible. When dried and ground into powder they can be mixed with cereals and used as flour. The roasted seeds can be used as a coffee substitute. The wood of ''Quercus glauca'' is a valuable fuelwood. Its leaves and stems are relished by deer.Heuzé V., Tran G., Lebas F., 2017. Blue Japanese oak (Quercus glauca). Feedipedia, a programme by INRA, CIRAD, AFZ and FAO. https://www.feedipedia.org/node/109

Gallery

Image:Quercus glauca4.jpg, Detail of acorns and buds Image:Quercus glauca MHNT.BOT.2010.4.2.jpg, Dried leaves and acorns

References

External links

photo of herbarium specimen at Missouri Botanical Garden collected in China in 1977

photo of herbarium specimen at Missouri Botanical Garden, collected in Myanmar (Burma) in 1961, showing rings on acorn cups
* * {{Taxonbar, from=Q714124 glauca Trees of Asia Flora of Indo-China Trees of Vietnam Plants described in 1784 Trees of Nepal Trees of Korea