Seeds are small, but powerful! Single seeds hitchhiking on the hulls of ships have led to disastrous biological invasions - so mailing them around the world can wreak havoc. Moreover, some seeds can be coveted, but collecting from rare specimens in the wild should be strictly avoided. By and large, avoid rare species, and ones which tend to be invasive.

Do also check the websites of your local customs department to make sure your exchange is legal. Lastly, if you think any member is offering certain illegal or harmful exchanges, do not hesitate to reach out to the YPS team and report them - we will look into it as soon as possible.