No, not bamboo, which is alien, but a native plant that can similarly form dense groves and grow to a height of 13 ft. (4 m): it’s Sesbania herbacea, for which a little searching has turned up the vernacular names slenderpod sesbania, bigpod sesbania, coffee-bean, Colorado river-hemp, coffeeweed, sesbane, danglepod, and bequilla. I photographed this colony of the plant of many names on the edge of a nameless pond at Southeast Metropolitan Park on October 30.
To see the places in the United States where slenderpod sesbania grows, you can go to The North American Plant Atlas, where the species is listed under its former name of Sesbania exaltata. (The maps there seem more up to date than the ones at the USDA. These newer maps aren’t clickable, but you can enlarge the page by repeatedly using your browser’s Zoom In command, which I suspect you’ll find in the View menu.)
UPDATE: I should have made it clearer that Sesbania is not a genus of native bamboo, but is instead in the legume family. Unlike grasses, legumes produce pods: much of the upper half of the photograph is filled with these plants’ long and slender pods.
© 2012 Steven Schwartzman