Before Xtine left to visit the Americas for Christmas, she gave me her (then thriving) poinsettia to care for. I warned her before she left that I had, what I term, a “black thumb.” I.e., if you put a plant into my care, no matter how much I try, I will end up killing it. I have no idea what I did wrong–I tried hard not to over- or under-water, I kept it in my rooms so it would have heat, and I made sure it didn’t have direct sunlight.
I guess that’s just the way the cookie crumbles sometimes. Or in this case, the leaf.