Belfast Botanic Gardens Tree Archive

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This series of short articles about trees in the Belfast Botanic Gardens is compiled by members of the Friends group and Gardens staff. We aim to build up to a comprehensive archive of trees in Belfast Botanic Gardens. Each article illustrates a tree growing in Belfast Botanic Gardens together with information from a range of sources. Where possible we will give the tree tag number - these are the small aluminium discs, usually fixed on the tree trunk, 2 to 3m above ground level.
Quercus cerris
Turkey oak or Austrian oak
Family: Fagaceae

Tag 86
54.58308N
5.934583W

Quercus cerris is a medium size tree (in the UK usually smaller than Q. robur ). Its leaves are deeply divided and it is distinguished by the mossy appearance of the acorn cups. It is one of the cerris section of the genus Quercus. The leaves are narrower than those of Q. robur and Q. petrea and along with others of the cerris group of oaks, it has soft bristles surrounding the shoot buds. It is a native from SE France across to the Balkans and Turkey.


It is one of the two hosts of the wasp Andricus quercuscalicis which, in another part of its life cycle, attacks native oaks (Q. robur and Q. petrea) forming 'knopper galls' which destroy the acorns. The pest is a recent introduction and can only breed where both Quercus cerris and native oaks grow close together. The knopper gall wasp arrived in Devonshire in the 1950's, expanding rapidly in 1979. It was recorded in Phoenix park Dublin in the 1990s and in Scotland in 1995. The wasp Andricus quercuscalicis injects an egg into the developing acorn in spring. The grub secretes chemicals which subvert the oak tree into producing a home for the grub instead of an acorn. The galls reduce the crop of acorns but do little damage to the adult tree. In 1998 the Ministry of Defence in the UK ordered the felling of all Turkey oaks on their property to protect the native oaks. Knopper galls are now frequently seen on the native oaks in the Botanic Gardens.

Quercus cerris in Belfast Botanic Gardens leaves of Quercus cerris
Quercus cerris in Belfast Botanic Gardens Leaves of Quercus cerris
Acorn cups of Quercus cerrisr Knopper gallcompared with normal acorn
Acorn cups of Quercus cerris Knopper gall on Quercus robur compared with normal acorn
Photos taken in Belfast Botanic Gardens in 2016 and 2018. Copyright: Friends of Belfast Botanic Gardens.

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