Yup, it’s coffee.

I can’t imagine that people wouldn’t want to take coffee with them across the galaxy. Even in Anne McCaffrey’s “Pern” stories, someone had to invent an alternative, “klah” (because coffee didn’t grow well on Pern) — and yes, people on different planets will have different drinks from just coffee. But some starship engineer or bioengineer, somewhere in the future, wasn’t going to stand for any substitute.

So “bitterberry” is a far-future descendant of coffee. The beans are not quite as fussy to process, and they are still used to make almost exactly the same hot beverage that people in our era know.