[m-i-l]

> "A blacklist would be very easy to implement and much safer from a legal point of view giving peace of mind to the app creators. All the invasive species are catalogued in public reports, to extract a list automatically from the pdfs should be trivial"

Or simply discourage international shipping. Personally I'd have thought a site like this would benefit from putting city and country at the centre of most activities, given how location-specific climate and even seasons are. That would also make it easier to support in-person activities such as plant swap meets.