Domestic plums are crimson to black-red with a yellow or reddish flesh; they are in season May through October. European varieties, which peak during the fall months, range from green to blue to purple and have a golden yellow flesh.
My plum tree is bursting with plums - I'm going to try canning this Martha Stewart Plum Butter recipe...This "butter" is cooked slowly until it is concentrated and deep red. It makes a wonderful breakfast, served with toast. My favorite butter: