Canna indica. They are often called "canna lilies" but they're not in the Liliaceae family at all. In fact, they're closer kin to ginger and bananas.
And, like ginger and bananas, cannas are edible (believe it or not). Their rhizomes contain the largest starch grains ever measured. The big leaves can be processed into fibers that make great paper. And it's just downright purty. The taller varieties of canna make a great visual barrier and they multiply from year to year.