Vetiver

 Native to India. Vetiver can grow up to 1.5 metres high and form clumps as wide. The stems are tall and the leaves are long, thin, and rather rigid; the flowers are brownish-purple. Unlike most grasses, which form horizontally spreading, mat-like root systems, vetiver's roots grow downward, 2–4 m in depth. This plant can be extremely helpful for erosion control.