We have some large stands of that stuff down here in Oklahoma ... they are an invasive species introduced from Southern Europe quite some time back, originally to be used as a source material for reed-based wind instruments and wickerwork.
The seeds of these giant grasses are 99.95% sterile .... only a VERY few may actually germinate and sprout. They grow and reproduce by creating nodules in their roots, to create offshoot plants that are nourished by the parent plant and continue to grow in a raft-like structure.
To get them to re-plant in a new area, the best method would be to cut several such root nodules away from a parent plant that already have a few shoots beginning to sprout, and plant them in the new area. They like very moist areas, especially near streams and roadside ditches that collect a lot of water ... their usual method of spreading is to have several root nodules and sprouts wash away together during a storm, to be deposited in another area downstream.
They have very little in the way of native competition and pests, being more of a silica-based plant structure (similar to rice stalks) ... it is thus supposed that the true source of these plants was originally the Far East and the Orient (China), though the most common assertion is that these came from the Southern Europe and Middle Eastern areas, since they exist there. The issue is ... the seeds from THOSE plants are non-fertile as well, so THEY must have been transplanted much further back in time.
