Gall

[mrs fish]

This is what the County Gall Recorder says

– I don’t think this is R.heterobia, but a ‘virescence’ i.e. a proliferation of the tissue of the catkin initiated by the presence of a virus. At least this is the current thinking as this growth was formerly supposed to be caused by a mite!

The shape is determined to some extent by the species of willow involved.

[spoonbillcourt]

I am pleased that we have those interested in Cecidology. When the Bird fair was held the day the new keys came out every book some 10,000 were sold out. I am sure there are many Gall enthusiast out there. In Annoying times thread I bet no one has mentioned odd looks when studying plant Galls.

I often get the chance to look around peoples gardens but I am always on the lookout for Galls.

As I said earlier there is much work to do n Galls and I was unaware of this one mention ed here. So you see we are still learning.

Gerry Bowdrey is the Suffolk Gall Recorder.

SBC

[ogwen]

sorry butting in here, just curious but what exactly is a gall? From what ive read from this post it sounds like a nest place for insects?

[spoonbillcourt]

A Gall is produced to hide larvae from Predators. It uses the plants as hosts and does no damage to the host at all. there are 1000,s of galls affecting many plants and are a whole study in itself.

Oaks have lots but Horse Chestnuts have none. Grasses, trees, mosses and even Fungi are all galled by insects.

SBC

[ogwen]

Ok thanks for that spoonbillcourt, interesting.
Ive noticed a few of those when ive been out, never knew what they were, until now

[poschiavanus]

Originally Posted by spoonbillcourt

A Gall is produced to hide larvae from Predators. It uses the plants as hosts and does no damage to the host at all. there are 1000,s of galls affecting many plants and are a whole study in itself.

Oaks have lots but Horse Chestnuts have none. Grasses, trees, mosses and even Fungi are all galled by insects.

SBC

Certainly one function of a gall is that it can hide an arthropod larvae from predators, although given the huge range of insects which emerge from a Robin's Pin-cushion it's not that effective (see hedgerow's blog

Much more important is that the galling organism (and it can be an insect, a mite, a nematode, a bacterium, a plant or a fungus (in a broad sense)) modifies the way the galled plant grows to obtain nutrients from the plant tissues. Some galls are even created by fluids secreted during oviposition by insects, rather than by the larvae themselves.

Galls take resources from the host plant: although they may end up preferentially on already stressed hosts. The widespread Knopper Gall on acorns of the English (Pedunculate) Oak can effectively stop the oaks from reproducing in some years. So they are not always benign.

Also, Horse Chestnuts are not gall free: although they might be pretty inconspicuous. The FSC key mentions a mite which causes small tufts of hairs on the underside of leaves in the angles of the veins.

A good selection of pictures of galls on oak and other plants is available at the Hainault Forest web site: HAINAULT FOREST

poschiavanus