Thunb. 1784 not F. Buerger ex Blume 1851 nor Martrin-Donos & Timb.-Lagr. 1864 nor Bosc ex Loisel. 1825 nor Oerst. 1869
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).
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, 6–13 cm long and 2–5 cm 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.
Cultivation and uses
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.
- illustration from D. Brandis, Illustrations of the Forest Flora of North-West and Central India, 1874
- Tropicos, Quercus glauca
- The Plant List, Quercus glauca Thunb.
- Flora of China, Cyclobalanopsis glauca (Thunberg) Oersted, 1867. 青冈 qing gang
- Heuzé V., Tran G., Lebas F., 2017. Blue Japanese oak (Quercus glauca). Feedipedia, a programme by INRA, CIRAD, AFZ and FAO. http://www.feedipedia.org/node/109
- 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
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