It has berries just a bit larger than peas, that ripen from green to very dark blue.
Wonderberries are somewhat sweet, and certainly far better tasting than Garden Huckleberries, with which the berries are often confused. That being said, and the name notwithstanding, the berries still don’t taste of much of anything when eaten fresh out of hand, and are consequently best used in preserves and pies.
Wonderberries are poisonous when green.
Wonderberries were developed in 1905 by Luther Burbank, who called them “Sunberries.” He sold the rights to them to another plant dealer, who renamed the berry to “Wonderberry.” Burbank had many critics, though, and some said that Burbank hadn’t really created a new plant at all, just renamed Garden Huckleberry (Solanum nigrum guineense), originally from Africa. Burbank backed up his claim of a new plant by saying that his was a cross between Solanum nigrum guineense and Solanum villosum (from Europe) that he had been working on for 25 years.