Blackberries are a wild berry variety that can be found locally in midsummer. Pick the darkest, ripest blackberries to enjoy the sweetest harvest. They contain vitamin A, while both raspberries and blackberries contain vitamin C as well as calcium and magnesium. "Blackberries and raspberries are very alkaline, high in iron, and are the best blood builders, although they can have a constipating quality." Dr. John Douillard. These cooling berries may help to combat diarrhea caused by the excess heat of the summer months. Delicious infused in water!