What grass can be as thick as a Japanese thatched cottage?

The reason why Japanese thatched cottages are so thick is that they are made of special grass materials, which can't be as thick and layered as ordinary natural grass materials. The natural red thatch from South Africa can not only achieve a thatched roof with a thickness of 5px-125px, but also has a life span of 3 years, which can be described as the exclusive grass material of Japanese thatched houses.