
Blackberries are dark, juicy berries, muddled or pressed into drinks for color, tartness and body.
A dark sweet-tart berry of any kind gets close, and blueberry is the mildest of them. Crème de mûre brings the flavor, the color and a lot of sugar, so it replaces the fruit and rewrites the sweetening.
Raspberries
Both are Rubus, and the difference is structural: a ripe raspberry pulls free of its core, a blackberry keeps its white core inside. That core is why blackberries hold their shape when pressed and raspberries collapse.
Mulberries
Longer, softer and easier to crush. Sweetness and acidity depend on the species: white mulberry is very sweet and almost flat, while black mulberry is genuinely tart and closer to a blackberry. It stains harder and muddles into pulp, so a drink built on it comes out cloudier whichever species it is.
A couple of days refrigerated, unwashed and uncovered enough to breathe, because trapped moisture is what turns a punnet gray. One moldy berry infects its neighbors within a day, so pull it out when you see it.