'Grass' in the Bible

The first angel blew his trumpet, and there was hail and fire mixed with blood, and it was thrown at the earth so that a third of the earth was burned up, a third of the trees were burned up, and all the green grass was burned up.

They were told not to damage the grass of the earth, or any green plant or tree, but only those people who did not have the seal of God on their forehead.