Here is a pic of the root of that big 4 and soil where I found that bunch of big plants/roots growing.
The spot where I found all of those big fat roots was on a east facing bluff, got a lot of direct morning sun and several hours of it, but then no direct evening sun. The soil there was WAY different too, just loaded with rock chips and I expect very high in calcium.
Just look at the root hairs on that root - it was very happy !
Also notice very short neck, just a few scars.
All of those big fat roots were found in that same spot on that bluff. Big heathly looking plants, big fat roots, very healthy looking and they all had only 6-8 root neck scars.
I think in this case growing conditions made most of the difference.
TNhunter