Man-Made plants (was Plant Snatchin')
Planty, except for the gene transfer from Caladium to Colocasia you mentioned, I wouldn't call the other examples man-made in the strictest sense. True, cross-pollinating aroids from different continents is not exactly likely, but what if a fly or a bee or other natural pollinator cross-pollinated the plants on your patio? I don't know about you, but I have plants from all over the world in my garden.
Now that's not to say that some of the really unusual hybrids and tissue-cultured plants aren't a huge pain to grow (at least in certain climates). What grows well here in Nevada never fails to amaze me, just as what doesn't grow amazes me. By tinkering with soil, watering, light and exposure, as well as providing a warm place to "wake up" dormant rhizomes, corms and bulbs of tropical plants in spring, I've managed to succeed fairly well. And if I don't, I try something else until I've killed a given genus/species/variety three times :-)