Originally Posted by PR-Giants

What you're describing I refer to as the "Dumbbell Effect" and it can be used very productively for macropropagation.

Basically a rhizome planted too deeply will self adjust the location of it's main growing point by sending up a slender growth containing the growing point to it's preferred depth. Once it's at that depth it will regain it's bulb like shape, it then resembles a dumbbell because it has two bulbs connected by a bar shaped growth.