As today’s photographer, Eric Hunt, points out, the Wikipedia entry on bitter melon is a good starting point to learn more about this widely-grown vegetable. It describes the plant, highlights the culinary and medicinal uses, and provides common names in two dozen languages. From the common names, it is easily inferred that it is cultivated pantropically (though African common names are absent). Kew’s Plants of the World Online, though not providing any African common names, provides a good scientific description of the plant: Momordica charantia.
An image search for Momordica charantia reveals a diversity of form for this vegetable. I think the hybrid in today’s photograph is one of the Indian cultivars. As always, though, I’m open to being corrected.
If you’re going to search for more information on bitter melon, you’ll find the search engine results cluttered with various medicinal claims, particularly in regard to diabetes. Do note that in Bitter melon (Momordica charantia): A review of efficacy and safety, Basch et al. (American Journal of Health-System Pharmacy. 60(4):356-359) conclude:
Bitter melon may have hypoglycemic effects, but data are not sufficient to recommend its use in the absence of careful supervision and monitoring