Ok, before you just dismiss this as just another flower, you should know this is a pretty cool plant. This is an Epiphyllum (or Hylocereus) Hybrid. It's a cactus similar to a christmas cactus, but bigger in every way. The pads are several feet long, and this blossom is about 9 inches across. His ancestors, were pure white and lived in one of the most unlikely places imaginable for a cactus, the canopy of Central American jungles, just like orchids (hence Epiphyllum, an epiphyte is a plant that grows upon another plant, like an orchid.) If that is not interesting enough, the large white blossoms of their ancestors bloomed in the evening for only one night. Why? Because their pollinators are nocturnal and some have fairly bad eyesight... bats and some large moths. I've always loved these plants. I have more than I really have room for, and each one is an amazing beauty.