When you go to the store and buy anything, do you know what is patented and what is not? Do you know every patent that covers every part of your phone? Do you know what parts of any of these things you can copy? Patent Law is just like that- 'academic' as you describe it, I suppose.
(I realize none of those things self-replicate like your seeds... but I think my point still holds.)
This article came up today and highlights quite nicely my unease about GM plants a. [0][1] If I stretch a bit, also kind of explains my unease about extending patent protections to plant life. The petunia flower with GM color change could be under patent protection. [2] Here we have a case of GM petunias growing outside a lab and quite likely breeding. What are the patent implications of patented plants going to seed? Does the landowner where the plant grows owe somebody money? If I'm a landowner, how do I identify and prevent patented plant life from growing on my property?
(I realize none of those things self-replicate like your seeds... but I think my point still holds.)