I thought i had a picture of local blackberries in bloom, but I'm still looking. Picture, for now, a prickly and bristly shrub with a few arching stems with several pretty white flowers. Repeat, thorny arching stems shooting out of brambles and thickets. White flowers with 5 petals and a hairy center. I do seem to have a pictures of the delicious berries, however.
Blackberries are part of a late-season group of fruits that are high in sugars.
The probable strategy here is for the plant to attract more mammals to disperse the fruits in rich dung. This forms a series of 'croquet wickets' that make getting to the middle of these prickly bushes quite difficult. It also affords birds a steady supply of blackberries despite people with buckets. Instead, bramble fruits are considered drupes, or fleshy fruits with stony pits. This explains the little aggravations that remain lodged in your teeth long after a blackberry-picking outing.