Fun Guy's picture

Oak tree growth

Observed: 24th May 2013 By: Fun GuyFun Guy’s reputation in Plants

This oak is in a pot in my garden. It has a lot of these berry like things on the underside of leaves and some on stems/twigs. The largest are about the size of a pea and in appearance look like unripe blackcurrants (without the little dry bit at the bottom). I've noticed there are some also on a large mature oak in my garden. I am assuming it is a caused by a parasite or insect. Any information appreciated.

Species interactions

No interactions present.

Species with which Oak (Quercus robur) interacts


PhilT69's picture

Oak Apples as we used to call these galls -

they go hard and woody (if its what I think it is). Caused by a gall wasp??

Phil T.

Fun Guy's picture

Oak Apples

Thanks. I haven't seen any for years and don't remember seeing them on the leaves only on branches as hard brown dry balls, but maybe that was because it was after the oak had shed it's leaves.


Ron Elliott's picture

Oak Marble Galls

I think that these are Oak Marble Galls caused by the gall wasp Andricus kollari. Have a look at

batwhittler's picture

Oak galls

If the galls are attached to the leaf surface they are probably cherry galls caused by the asexual phase of the wasp Cynips quercusfolii.

Andricus kollari usually affects the buds of oak.

The activities of the wasp larva cause the plant to produce extra plant tissue on which it feeds until ready for the next stage in the life cycle.

darob57's picture

Currant galls maybe

These may be the sexual generation galls of Neuroterus quercusbaccarum, known as currant galls. The same species of gall wasp (asexual generation) causes spangle galls on the underside of the leaves later in the year.
As well as growing on leaves, currant galls appear on the male flowers.

Cherry galls caused by Cynips quercusfolii appear later in the summer.


petershirley's picture

The last comment above has it

The last comment above has it right.

Peter Shirley