Solanum pyracanthos is native to Madagascar and is a member of the genus that includes tomatoes, potatoes and eggplants. I wouldn’t try to eat the small fruits without a good indication of their edibility, however, as many members of the Solanum are poisonous (at least when raw).
Solanum is one of largest genera of flowering plants, with about 1500 species distributed across all continents except for Antarctica. Solanum pyracanthos is a member of the subgenus Leptostemonum, or spiny solanums. Members of Leptostemonum usually have prickles, long tapering anthers, and star-shaped trichomes (hairs). There are 76 native spiny solanum taxa in Africa and Madagascar. Until recently, their identification and phylogeny were unclear. In 2012, Vorontsova et. al. published African spiny Solanum (subgenus Leptostemonum, Solanaceae): a thorny phylogenetic tangle. This study represents the first research focused on the evolutionary history of the spiny solanums in Africa and Madagascar. Vorontsova et. al.’s analysis confirmed that the Old World Leptostemonum is a monophyletic group (clade)–meaning that all members of the group evolved from one common ancestor. Within the old world spiny solanums, the authors tentatively place Solanum pyracanthos in a clade composed of all of the Madagascar species of Solanum, even though these species are morphologically dissimilar.
Solanum pyracanthos, also known by the common name of porcupine tomato, is a cold-intolerant shrub that reaches a height of 1-2 meters. Its stems and leaves are covered with prickly orange spines that are purple at the base. Some gardeners grow porcupine tomato for the novelty of its pinnately-lobed leaves and bright spines, but growing this species takes a bit of effort. In warm climates, Solanum pyracanthos can be quite weedy and gardeners are advised to remove the fruits. However, in temperate climates, it must be coddled in much the same way as tomatoes do.
The purple, star-shaped flowers of Solanum pyracanthos have connivent anthers (the anthers are touching but not joined). Their anthers are also described as poricidal; the dry pollen is only accessible through a small opening at the tip of the tube-like anther. Such flowers (labeled Solanum-type, irrespective of the genus) are pollinated through buzz-pollination, or sonication, in which the bee must vibrate its wings and muscles in order to knock out the pollen. This intense vibration generates forces of up to 30 G! Sonicating bees make a characteristic sound, captured beautifully in a video posted on the Leonard Lab website. I can recall hearing the sound of bees sonicating many times, but I didn’t know what I was hearing until seeing (and hearing) this video. Interestingly, not all bees sonicate–honeybees are not good pollinators of most Solanums, which is why commercial greenhouses typically pollinate their tomato crops by hand or with bumblebees.