By Ladyessex1
Leigh-on-Sea Essex,
United Kingdom 
ID.
I have these Blackberries growing in my garden but the leaves are so different to other Black Berry leaves, I was wondering what variety they could be?
15 Aug, 2017
I'm thinking Rubus laciniatus, probably with manganese deficiency. If the soil is acid or neutral, Ladyessex, add some volcanic rock dust. If chalky (alkaline) add compost to reduce the pH, and re-evaluate once it's down.
15 Aug, 2017