Root cap. Coloured scanning electron micrograph (SEM) of the root cap of wheat, (Triticum vulgare). The root cap produces a slimy mucous that lubricates the passage of the root through the soil. The cells that produce the slime are continually sloughed off, a mechanism that enables the constant renewal of this protective layer. The cells at the root tip are firmly embedded in slime (blue), while further back loose cells are shed. Root hairs, seen in the background, appear at a distance behind the tip and greatly increase the roots absorptive surface area. Roots anchor a plant in the soil and extract water and nutrients. Magnification: x220 when printed 10 cm tall.