Where do root-over-rock roots go?

When developing a root-over-rock composition, when the roots reach soil level, do the roots go outwards like a proper nebari, or do they dive straight into the mix?

Paul

I think in most examples I have seen the roots went directly into the soil. The design purpose of nebari is to show the tree anchored to the earth, it also does that by wrapping the roots on the rock. I think a flared nebari on a root over rock planting would be redundent.

I think Billy's right . . . however, I can envision a fig (for example) with its roots twining around a tall stone, then spreading out into the soil around the stone.

Thanks for the replies. I've seen pictures of good root over rocks, but never seen one in the flesh, so to speak. The pictures don't give much indication about what happens at soil the level.

My problem Jim, and Billy, was that I can imagine both of your scenarios. I have seen roots growing down a rock and across the ground in a rain forest, and also seen them just disappear into the ground. Maybe its one of those not right, not wrong type of things, but depends on the composition.

Thanks again.

Paul

My problem Jim, and Billy, was that I can imagine both of your scenarios.

Well then. That's your challenge, isn't it? To find a rock and a tree and to decide which of the "scenarios" (or another one entirely) would fit that tree and that rock.

Just any tree and any rock never works.

A good root spread on a tree at the rock soil interface would look good (even if it is redundant).