N. odorata is particularly tough and adaptable in northern areas (and considered a nuisance in Washington State), and N. tetragona, the pygmy waterlily, while small, actually grows naturally in many parts of Alaska. The first one is at Texas Waterlilies, but the second is more challenging to find. It's easier to locate some of its cultivars, such as Joanne Pring and Grandiflora, but I don't know if those cultivars are as tough as the original.
