Got a mystery plant? Try FlowerChecker
"With this app, you can take a picture of an unknown plant and get it identified by an international team of plant experts. The identification is not computer-based, our team will try to solve it as soon as possible, but it usually takes minutes or hours to respond. So far, we have been able to identify 85% plants in average.
There is no charge when we fail to identify your plant, but a little fee applies when you decide to display the name of an identified plant. Nevertheless, everybody gets two identification points for free as a trial."