Simply put, the ply number represents quality and the higher the number, the higher the quality. For instance, three-ply has better quality than the two-ply regardless of whether they come from bamboo or sugarcane green forest materials. A one-ply bamboo toilet paper comes in as a single layer which is thinner than the 2 ply or 3 ply which comes in three layers of a roll. The thickest tissue paper with the highest number of plies tends to be the most eco-friendly toilet paper.