This has happened a few times since we've had the plant, but I've never quite been able to figure out how it gets pollinated. I don't remember ever trying to self-pollinate it (which is weird, actually, and unlike me), and most of the time we don't have any insects around which would do it (certainly not during winter). I couldn't find anything definitive on-line as to whether M. paniculata ought to be able to self-pollinate in the first place. I mean, clearly it must -- we only have the one plant -- but it seems like if it's able to self-pollinate then it really ought to be doing it way more often than this.
As it is, we see fruits on the plant about once a year, usually in the winter, and generally it's only one fruit per round. This year is special because there are two fruits at once. They look pretty identical in the photos, but there really are two of them.
A reader sent me a M. paniculata fruit quite a while ago (last spring? Summer?). I got one seed out of it, and tried to sprout it, but didn't use vermiculite (I know! What was I thinking?), so it dried out a lot, and may not have even been viable in the first place. I'll definitely try again with these, whenever the time seems right to do it, because nobody sells this here anymore. We couldn't even get it at work, due to the Florida quarantine for citrus greening. So if I want more of them (and I do: oh, my, how I do), I'm going to have to figure out how to propagate them from this plant. Cuttings are said to be possible, but difficult, and the husband discourages me (strongly) from hacking the plant to pieces, so I don't have a lot of opportunities for experimentation. Seeds are my best bet at the moment. Let's hope there are some viable ones in there.