I think I've identified this, but my plant looks different than the ones that I've been able to find on the Internet. Please have a look and tell me what you think. This is September 23, 2017 and I took this photo today. This plant bloomed normally all summer but for some reason suddenly developed these green flowers.
I will probably destroy the plant since it can be a vector and infect other plants, not sure which ones yet but it's gotta go.
It's actually sort of pretty.
