This could be a bit more complicated... one of the trade/sell options is for seed of a plant. Is there a way to include hybrid seed that would require listing of both parents? This would be used by hybridizers for lilium, iris, daylily etc.
The user would need to be able to list a pod parent and a pollen parent (for named parents maybe this could be clickable). For second and higher generations, fillable. Or all fillable maybe. It would have to be flexible, kind of like the discussion about where a plant is located in the yard (such as a comment box for additional information about the seeds).
I'm just tossing this around in my head right now but wanted to touch base.