rhizomes and a stolon

the german butter ball in the top photo and the all red in the second were chitting away eight days ago when i planted them and they haven't really slowed down since...neither has leafed yet but both have been busy producing rhizomes as they expand their root systems...the roots emerge from the top of the seed tuber which is why the plant will produce no tubers deeper than the depth the seed tuber was planted at...so we hill them to stimulate the growth of more rhizomes and so spuds...the ollala in the third photo had produced a rhizome very close to the surface in a container that is pretty much already filled to capacity with soil...i tried to cover it but it found the light and became a stolon...and now i am fairly sure it isn't even a stolon anymore...it has begun to leaf ( not a bad thing...a little more energy expended but more leaves to feed the roots should translate inot more spuds ) so i will have to call it a stem...potato progress downstairs.