smut-grass

from The Century Dictionary.

• noun A rush-grass, Sporobolus Indicus, widely distributed through the warmer regions of the world, and common in many parts of the southern United States. It grows in scattered tufts and patches in dry open fields. The slender leafy stems soon become woody and tough, unfitting the plant for forage. The long and slender spike is usually blackened by a smut (Helminthosporium Ravenelii), whence this name and that of black-seed grass. Sometimes called carpet-grass.