Quercus glauca

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Ring-cupped oak
Quercus glauca Bra65.png
1874 illustration[1]
Quercus glauca4.jpg
Scientific classification edit
Kingdom: Plantae
Clade: Angiosperms
Clade: Eudicots
Clade: Rosids
Order: Fagales
Family: Fagaceae
Genus: Quercus
Subgenus: Quercus subg. Cyclobalanopsis
Species: Q. glauca
Binomial name
Quercus glauca
Thunb. 1784 not F. Buerger ex Blume 1851 nor Martrin-Donos & Timb.-Lagr. 1864 nor Bosc ex Loisel. 1825 nor Oerst. 1869[2]
Quercus glauca - MHNT

Quercus glauca (syn. Cyclobalanopsis glauca), also known as ring-cupped oak, Japanese blue oak or glaucous-leaf oak, is an Asian species in the genus Quercus in the beech family. It is native to eastern and southern Asia, mostly in China but also in neighboring countries (Afghanistan, Kashmir, northern and eastern India, Nepal, Bhutan, Myanmar, Vietnam, Korea, and southern Japan).[4]

Quercus glauca is a small to medium-sized evergreen broadleaf tree growing to 15–20 m tall. The leaves 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 flowers are catkins, and the fruit are acorns 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).[4]

Cultivation and uses[edit]

It is planted as an ornamental tree in regions of Europe and North America 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.[5]


  1. ^ illustration from D. Brandis, Illustrations of the Forest Flora of North-West and Central India, 1874
  2. ^ Tropicos, Quercus glauca
  3. ^ "Quercus glauca Thunb.". World Checklist of Selected Plant Families (WCSP). Royal Botanic Gardens, Kew – via The Plant List.
  4. ^ a b Huang, Chengjiu; Zhang, Yongtian; Bartholomew, Bruce. "Cyclobalanopsis glauca". Flora of China. 4 – via eFloras.org, Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.
  5. ^ 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

External links[edit]