Plants don't absorb anything from rocks that make them weak and soft. It's the other way around: rocks break down and weather due to the action of plants and other biological processes.

Here's how it works:

* Root Growth: Plant roots grow into cracks and crevices in rocks. As the roots grow, they exert pressure and can physically break the rock apart.

* Chemical Weathering: Plants release acids into the soil through their roots. These acids can react with the minerals in rocks, dissolving them and breaking them down.

* Lichens: Lichens are a combination of fungi and algae that grow on rocks. They produce acids that can erode the rock surface.

* Bacteria: Certain bacteria can break down rock minerals, releasing nutrients that plants can use.

So, instead of absorbing something from rocks to weaken them, plants actually contribute to the process of rock weathering. This weathering plays a crucial role in soil formation, which is essential for plant growth.