I believe that the root structure becomes larger over time and stem will put on circumference as it ages.
It would not be noticeable until it where raised years down the road, then you would have a
now exposed Caudex. Many used to say that cuttings would not produce a wider caudex.
As long as the roots are subterranean, they are roots. Once exposed and above the soil, now the Caudex.
Probably not something you did not already know.
Rick
