This is a variety of Japanese Timber bamboo but only gets about half as large. A small percentage of the canes have a “zig-zig” at the base thus the name “Slender Crookstem”. I assume it’s called slender as the canes of this variety get to about 3 inches in diameter while the species gets up to 6 inches in diameter. Since only a small percentage of the canes have the zig-zag it can be difficult to tell the difference. We have several groves of this bamboo near the nursery and it seems to be quite common in the southeast. The image below is of a grove nearby that covers about an acre. It bordered on two sides by power-line right of ways and on another side by a road. This has kept the bamboo grove from extending even further but the other side is a yard and in the picture you can see it is just waiting to take over if the owner ever stops mowing! It is a very impressive grove and fun to walk through as the canes are very dense and it is quite dark once inside. ”