Maybe skunk smell would be worth doing. So many people talk about the good skunk in the old days. Also, something easy for people to spot. Just pass the seeds from the skunkiest female.
To be open source, your want a new model. Something like, give all participants a number and some seeds. They grow them out, and pollenate. Pass some seeds from your skunkiest female to the person with the number above you. Maybe even hold your pollen at that point for the next round. That way nobody holds all the seeds, and if anyone drops out or disappears, you just remove or replace them.