I'm going to guess that it is a literal reference from ye olde years ago. Suspect that square racquet lawn tennis or jousting stick iron boys competitions paired up into matches by pulling numbered seeds out of an opaque cloth bag. At some point, some bespectacled enthusiast might have suggested that competitors with more success than others deserved a higher ranking on a matching tree and "seeds" were carried over as the non-clementure.

*citation required...I completely guessed this