That looks more like Chinese golden bamboo, aka fishpole bamboo (Phyllostachys aurea). There scads of it around here, it's naturalized all up and down the rivers. I've made some fairly good arrows from it before-the trick is finding shoots small enough without the big flat dished in areas above the nodes. How big are the biggest plants? if you could post a pic of the whole thing it would be easier to say for sure.