Try out Flora Incognita, it usually works pretty well, at least in the UK. Though I'm kinda bemused that while often I give it one blurry photo of a leaf and it immediately spits out the 97% confidence answer (and yes, the result's example photos do match the real plant's other parts too), but occasionally it has me take painstaking photos of like 5 different aspects of the plant, then thinks for more than a minute and goes "eeh, 37% that it's this [completely different looking] plant, otherwise no clue".