(Blaeberries: AKAs bilberries, whortleberries) Wash, trim and roughly chop the rhubarb, put it into a pan and cook gently until it starts to soften. Stir in the sugar and when it has dissolved add the blaeberries and bring the jam to the boil. Boil it rapidly for up to 20 minutes to setting point. Cool slightly then pour into clean warm jars, cover, label and store. (Test for setting point: test the jam by placing a spoonful on a plate, letting it cool and then pushing the surface with your finger: if it wrinkles the jam is ready)