What term describes structures built on the ground to support a tree branch or trunk?

The term that accurately describes structures built on the ground to support a tree branch or trunk is "props." Props are temporary or permanent structures used to stabilize limbs or trunks that may be weak or at risk of breaking. Their purpose is to provide physical support to the tree, helping to maintain its structure and integrity, especially in adverse conditions or when the tree is facing structural issues.

While the other options refer to various forms of support, they don't specifically capture the essence of ground-based structures as props do. "Braces," for instance, are typically used for internal reinforcement rather than being ground-supported. "Supports" is a more general term that could encompass various types of assistance but doesn’t pinpoint the nature of support that props provide. "Stands" usually implies a more general base and may not directly relate to the specific act of supporting tree branches or trunks. Therefore, "props" is the most precise term in this context.