The best identifying characteristic will be the flowering tops. The flowering tops have a fluffy, "bottle-brush" like appearance. These "bottle-brushes" are many small and light seeds that are well adapted for wind dispersal. Pennisetum setaceum has a very similar appearance to one of our native bunch grasses, Purple three-awn, Aristida purpurea. Don't be confused; Purple three-awn won't have the "bottle-brush" flowering heads. Aristida purpurea is also softer and smoother if you run you fingers along its blade margins.