A throwback. Nice.
I'm heavily involved in a C4 grass industry and stuff like this was required reading. In the comments, the Americans refer to it as "tallgrass" but ours is different due to its tropical nature.
It will be hard to break the simple idea that deep roots means water retrieval. I'm in the carbohydrate storage camp, a grass stores its reserves temporarily while the going is good as an insurance policy for fire or tough times. The C4 grass we use is far more persistent into Australian droughts than other exotic C4s (selected for vigour by pastoralists), the difference being the root physiology.
