Absolutely beautiful ending. I don't even necessarily know if I'd call it "tragic", because the two of them were ultimately able to be together, in the end. When the boy was confessing to the teacher, he mentioned that she was retiring at the end of the year, so I wonder if the teacher had known about/been planning to turn into a flower to be with the girl for a while by that point... Also, the foreshadowing with the hands wrapped in the bandages...
I swear to God that Shinoa is one of the best yuri artists of this generation, she consistently puts out banger after banger.