The Collaborative International Dictionary of English v.0.48:

Gama grass \Ga"ma grass`\ [From Gama, a cluster of the Maldive
   Islands.] (Bot.)
   A species of grass (Tripsacum dactyloides) tall, stout, and
   exceedingly productive; cultivated in the West Indies,
   Mexico, and the Southern States of North America as a forage
   grass; -- called also sesame grass.
   [1913 Webster]