First created in 2009, Pl@ntNet is a social network for plant lovers, as well as a plant identification app.
Once a user makes an identification (or marks the plant as unknown), they submit their photos to the Pl@ntNet community. Thousands of professional botanists and flora-philes scan the stream of new observations to verify a species, or suggest a new one. If a person confirms your observation, a little green “crowd” icon appears. Your score rises as more people validate your labels, although a few users are certified to train the algorithm without community validation.
I haven’t used this yet but I’ll definitely check it out. I also love iNaturalist. It’s not really a social network, but it can identify both plants and animals.