Victoria amazonica is probably the best known of these aquatic lily pads that get so huge (almost ten feet wide) they can support the weight of small children.
If you happen to have room for these giants, they can be cultivated in Tucson. Even in the Amazon they are short lived perennials. So expect to replace often. They are indeed very frost tender.
Yes there is a support group of water plant nerds you can collaborate with if you are thinking of putting in a water pond.
The first time I encountered these was surprisingly in Phoenix, in a water pond at some state building. I couldn’t talk for some time. They are AMAZING plants.
Pollinated by scarab beetles (!) the flowers are white the first night, and pink on the second.
Plants can be obtained online, if local water plant sources fail you. But they are a bit pricey.