This bamboo-looking stem plant is not a grass. It comes from Asia, where it often grows in rice fields.
The growth is upright, but the plant branches out willingly when it is cut back. 
The leaf is light green, approx. 1cm wide and 3-5cm long. The stem apex becomes reddish when exposed to CO2 and strong light. 
Due to quick growth, the longest shoots require ongoing cut back and some of the tops can be replanted, in order to maintain a beautiful and varied group of plants.