Tropical Blue Bamboo (Bambusa chungii)
That particular plant is located in Florida. If you go to the American Bamboo Societies web page and then go to the Florida - Caribbean Chapter or
and look under Bambusa Chungii you will see it.
That plants offspring however is in Southern California and looks just like it only smaller. The Southern California Bamboo Society Chapter has sales twice a year on the third Saturday of April and September at Quail Botanical Gardens in Encinitas and from time to time rare plants such as this come up for sale. That is where I got all of my bamboo from.