I finally got around to buying potting soil and repotted a few plants. Including this one- which I now think might be an amaryllis? or something related.
Most of the other houseplants just got a top-off with the new, richer soil- parlor palm, avocado, geranium, etc. The one I really worked on was my poor jade.
It's suffering. I have cut back bug-infested foliage so much, and it feels futile. I have sprayed with soapy water. I finally upended it, discarded all the soil, disinfected the pot, soaked its entire crown in dishsoap water, and cut it back hard. The stems do not have good tone- they feel a bit soft. And the root mass was smaller than I expected- so I actually put it back in a smaller pot. Close inspection I think I have finally identified the culprit- aphids. They're kind of a dark blue-gray color and most aphids I've seen before were bright pale green so maybe that's why I didn't realize what they were before.
Because I found them on all my peppers and on the sweet potato plants, too. I think I've been harboring these pests in this corner all winter! Today it was very warm but a bit overcast- I took the above-mentioned plants outside for cleanup. Trimmed off all the dying foliage, cut back the peppers to balance them out, sprayed heavily with the dishsoap mixture. Hoping for recovery.