Quercus glauca

Quercus glauca (syn. Cyclobalanopsis glauca), commonly called ring-cupped oak or Japanese blue oak,[4] is a tree in the beech family (Fagaceae). It is native to eastern and southern Asia, where it is found in Afghanistan, Bhutan, China, northern and eastern India, southern Japan, Kashmir, Korea, Myanmar, Nepal, and Vietnam.[5]

Ring-cupped oak
Quercus glauca Bra65.png
1874 illustration[1]
Scientific classification edit
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Rosids
Order: Fagales
Family: Fagaceae
Genus: Quercus
Subgenus: Quercus subg. Cyclobalanopsis
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]
  • Cyclobalanopsis amamiana (Hatus.) Masam.
  • Cyclobalanopsis glauca (Thunb.) Oerst.
  • Cyclobalanopsis globosa T.P.Lin & T.S.Liu
  • Cyclobalanopsis repandifolia (J.C.Liao) J.C.Liao
  • Cyclobalanopsis sasakii (Kaneh.) Kudô & Masam.
  • Cyclobalanopsis vibrayana (Franch. & Sav.) Schottky
  • Perytis glauca (Thunb.) Raf.
  • Quercus amamiana Hatus.
  • Quercus bambusifolia Fortune 1860 not Hance 1857
  • Quercus dentosa Lindl. ex Wall. name published without description
  • Quercus globosa (T.P.Lin & T.S.Liu) J.C.Liao
  • Quercus ichangensis Nakai ex A.Camus
  • Quercus lacera Blume
  • Quercus laxiflora Lindl. ex Wall. name published without description
  • Quercus longipes Hu 1951, not Steven 1857
  • Quercus lotungensis Chun & W.C.Ko
  • Quercus matasii Siebold
  • Quercus repandifolia J.C.Liao
  • Quercus sasakii Kaneh.
  • Quercus tranninhensis Hickel & A.Camus
  • Quercus vaniotii H.Lév.
  • Quercus vibrayeana Franch. & Sav.


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).[5]

Cultivation and usesEdit

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.[6]



  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. ^ Quercus glauca North Carolina State University
  5. ^ 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.
  6. ^ 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 linksEdit