Some of the drawings do seem to show how different soils impact root growth. For example, see https://images.wur.nl/digital/collection/coll13/id/1288/rec/... Is there another explanation for the root structure in this drawing? It would have been nice to see this reflected in the metadata to make it more easily findable.
That's really cool. The tree sends out a root tendril in that location and when it encounters better conditions, that tendril becomes the main source of gathering and it expands and builds.