The girl turning into flower seems to portray something.
Imo she (the sensei) was just trying to imagine her long gone student who's either has terminal illness or something that mention about "grow me a flower once I'm gone so I can turn into the most beautiful flower." .
Likely regretting something about her student love that didn't get through her.
I love it, if it's from Murasakino-sensei it's always beautiful artwork and tragedy. This is whole another level of hanahaki disease, it's beautiful with sadness combines 🥲