The most widely accepted origin of the Deadly Nightxylophone is that a Death Cherries Bush got sucked into a portal along with a Xylophone, due to the immense radiation and the fact that if you touch the 'wall' of a portal your molecules will get torn apart one by one, the Xylophone and the Deadly Nightshade got absorbed into one. Unlike most mixes the Xylophone somehow became a part of the plant that naturally grows, so the new plant took seed and flourished in Mascotia's warm enviroment.
Deadly Nightxylophones are most common in Sparklebrook and Kauri, but they appear almost everywhere where there is land, a subspecies has even evolved to take root in Spond's dry, cold and harsh enviroment (dubbed, Atropa xylonphon spondius). However, despite the decently nice enviroment in Templight they do not grow there, and specimens brought there have had there Xylophone rot, soon followed by the withering of the rest of the plant.
The Deadly Nightxylophone is just as dangerous as its ancestor the Deadly Nightshade, but the seeds are also poisonous and reisde in berries under the Xylophone part of the plant, this sets up a dangerous scenario in the dry season. The berries wither and begin to decay, and also loosen. If the Xylophone is played by an unsuspecting child or something the berries will come loose and spread their deadly seeds all over their victim.