What is the function of a root cap?

The root cap is a special layer of tissue which protects the tip of a growing root and helps to anchor the plant. At the very tip of the root is a loose mass of parenchyma cells which continually slough off and regenerate with the growth of the root system. In addition to protecting the interior of the root, the cap secretes a mucilage which stabilizes water content of the surrounding soil, ensuring longer-lasting nutrition to the root system and making for easier root probing. Finally, the root cap contains statocytes, which are specialized cells that help the plant to sense gravity and grow accordingly. These cells are full of starchy organelles which settle at the lowest part of the cell and encourage growth in that direction. If the root cap, with these statocytes, is removed, plants may grow in random directions because it has lost the ability for gravitropism. 
http://www.plantphysiol.org/content/plantphysiol/120/2/343.full.pdf

https://www.britannica.com/science/root-cap