Paul, that looks like some kind of
Phyllostachys bamboo. There are several different ones that are naturalized, it's all over around here. It makes decent arrows, but not as good as rivercane, bambusa, or Jap arrow bamboo. Here is the USDA map for rivercane distribution in Tejas:
PS-I packed your box of rivercane up this morning, I'll put it in the mail Monday.