What on earth is this red thing?

[grass routes]

Whilst picking dog rose petals in our local community orchard, I found a large number of these red chestnut-casing looking things attached to the branches. Can anyone tell me what they are as I have poured over the wild flower guides with no success. Many thanks!

[Capsid]

It's a gall caused by the larva of an insect living within the plant. What plant is it on, then it may be specifically identified?

[vicky]

Gall wasp - Wikipedia, the free encyclopedia

yes, as caspid says, rose gall

[la cebolla grande]

Its called Robin's Pin Cushion. It is common on roses, usually dog roses and single flowered varieties. Its common in the 'wild' in UK - and is totally native. It won't hurt the plant at all, so don't worry about it!

The female wasp will have laid her eggs in the stem of the plant and (clever things) each gall wasp produces a hormone that mimics a plant growth hormone. This cause the plant to grow into the fantastic gall shapes - each one unique to a particular species of wasp. As the gall is made up of the plants own material it doesn't cause any harm.

LCG

[Flummery]

My son has a great interest in galls - strange boy! On a country walk we are plant spotting - he is deformity spotting! In the world of galls the Robin's Pincushion is one of the most attractive I think.

[grass routes]

Many thanks for the info! There were about 12 of these Robin's Pincushions on the dog roses in a quarter mile square. These were all located in an organic historic apple orchard in Hertfordshire which is next to a gorgeous meadow of wildflowers. Naturally, it is under threat from developers (there is no part of the M11 corridor that isn't) and part of me wished that these galls were rare specimens of some sort to protect the land. I am glad to know what they are though.

[seasprout]

It is the prettiest of all the Gall's in my opinion.