1) PI grass 
• (n.) A tall, coarse grass (Imperata arundinacea) of the Philippine Islands and adjacent countries, used for thatching.
Co·gon' noun [ Spanish , probably from a native name.] A tall, coarse grass ( Imperata arundinacea ) of the Philippine Islands and adjacent countries, used for thatching. 
a tall, coarse grass, Imperata cylindrica, of the tropics and subtropics, used widely for thatching.