I am a wildlife biologist, and also a collector of WW2 militaria. I live in Alaska and have lived in northern Europe, but have little experience with tropical plants. I believe the material on this Japanese helmet cover is sugarcane, but I am thrown off by the serrated edges, as can be seen in these pictures. I only know that this item was brought back by a US Marine at the end of the war. From the characteristics of the cover, I am guessing it came from Okinawa. Does anyone know what species of plant this is, and if so, where it occurs? The leaves are very old and brittle. Thanks, Scott