Boing Boing quotes from an article in Intellectual Property Watch that examines how Brazil is fighting against the big pharmaceutical companies that are trademarking plants.
This means that a guy in Brazil who prepares the local plant and serves it to local customers, using the name of the plant (now trademarked) gets sued by the big pharma company. But Brazil is taking steps to stop this from happening, and they've even proactively published a list (in Portuguese) of native plants that they won't allow foreign companies to trademark.
I think this is a great step for Brazil to take. How effective it will be, in terms of each countries' patent authorities enforcing it - who knows. But it is proactive.