There are some species of orchid that resemble females of certain insect species in order to be pollinated by deceived male insects.
Skunk cabbage (yes it is a flower) is part of a small group that give off heat.
Mayapple seeds are disseminated by box turtles.
A giant carnivorous pitcher plant was recently discovered in the Philippines that is big enough to occasionally dine on small mammals.
There is a class of perennial flowers called spring ephemerals that come up in early spring in profusion for a few weeks in forests before trees get their leaves and then go back below ground. Examples where I live include Virginia blue bells, spring beauties, blood roots and woodland poppies. Many people are unaware of these flowers. I would encourage people to go outdoors to nature preserves to seek them out.