The blackberry (botanical species Rubus) belongs to the extensive rose family. The fruits, which are usually blue-black when ripe, are botanically speaking not berries but aggregate drupes that form from the individual carpels. Each of the small individual berries is similar in structure to a drupe (e.g. a cherry) and has a thin outer skin like the latter. In fact, when you chew the fruit, you bite on small stones, which also contain the seeds of the blackberry. Unlike the raspberry, the fruit is firmly attached to the base of the flower. The fruit ripens from August to September.