They are all raffia palm leaves stripped into threads. Both brands are treated and appear a little waxy. However, MoMarsh Invisgrass is the only one I have seen that has stated they are treated for mildew resistance.
I always hang my raffia sections to allow them to dry between uses. Anytime they are left to sit in water they get a little funky, but not nearly as funky as natural grass.
This fall Cabelas had their prarie grass on sale for the layout blind size bundles. It is raffia as well. It turned out that their "wheat field" green is fluoresent green and about 40% of the threads in the bundle are bleached white and not a natural tan like raw raffia usually is. Might as well as painted the boat white once it was grassed up. I will solve the issue this spring with some Rit dye using the Steve Sutton methods.