Height was 2m. Racemes large and open with lower branches to 10 cm long. Definitely perennial - see rhizomes in pic2 where I dug some stems. Spikelets are paired, one right against inflorescence axis, the second narrower one on a pedicel a few millimetres long. Spikelets 6mm and more, awn to 10 mm from the lower floret. This well established patch has about 100 stems but probably far fewer individual plants. Seed heads were removed after taking photo.