Ray grass : A perennial European grass (Lolium perenne); -- called also rye grass, and red darnel. See Darnel, and Grass.

Example:


Taxonomy
displacement, map, grass, mental ray, ground plane, grass texture, noise modifier, final gather, shader, procedural, tutorial, the noise, subdivision, adjusted, DGS, slot, grass surface, Edge length.

Defination from the web:
Grass Displacement with Mental Ray. By Jeff Patton. In this tutorial I will explain how to create grass by using the Height Map Displacement map. ... I will add my grass texture to the DGS surface, NOT the mental ray surface. ...