Hetty, They call them Centipede root trained, because of the main roots all around the outside of the caudex, like the one that Kadie has. Lucky girl
Most of what you see in Thailand are produced with Thai Socotranums and some Arabicums.
They lift and cut the base of the tree (trees are what they refer to them as) all roots off.
Dry, treat and replant to produce a circle of roots around the perimeter of the caudex.
They raise the trees over the years, taking the roots (have to be hung for 3-4wks., so the roots become somewhat malleable) and placing them where they want creating a really cool appearance.
This a borrowed photo, not mine.
I believe that many of these are being produced for outside of Thailand. Most of the Thai Masters like Natural roots as opposed to centipede roots.
They raise them almost giving them a 'mountain top' tree.
Rick