Short answers, pulled from the story.
Carnivorous plants derive some or most of their nutrients from trapping and consuming animals or protozoans, typically insects and other arthropods, and occasionally small mammals and birds. They have adapted to grow in waterlogged, sunny places where the soil is thin or poor in nutrients, especially nitrogen, such as acidic bogs.
True carnivory is believed to have evolved independently at least 12 times across five different orders of flowering plants. The oldest surviving lineage dates to 85.6 million years ago, while the youngest, Brocchinia reducta, is estimated at only 1.9 million years ago.
Carnivorous plants use five basic trapping mechanisms: pitfall traps such as pitcher plants, flypaper traps that use sticky mucilage, snap traps that use rapid leaf movements, bladder traps that suck in prey with an internal vacuum, and lobster-pot traps that use inward-pointing hairs. Each is a separate solution to capturing and holding prey.
The Venus flytrap, Dionaea muscipula, has three trigger hairs on each lobe, and bending one opens stretch-gated ion channels that fire an action potential to the midrib. Changes in cell shape let the tensioned lobes flip from convex to concave in less than a second, and two stimuli between 0.5 and 30 seconds apart are required to prevent false closures.
Carnivorous plants grow in bogs because carnivory only pays off where soil nutrients are extremely limited but light and water are abundant. Reshaping leaves into traps lowers photosynthesis and raises respiration, so the plants are poor competitors that succeed only where other plants fail.
The Man-Eating Tree of Madagascar, also called Crinoida dajeeana, was a literary fabrication that first appeared in the New York World on the 26th of April 1874. It was credited to an invented German explorer named Karl Leche and described a woman sacrificed to the tree by the fictional Mkodo tribe; the explorer, the tribe, and the tree were all fabrications.
Charles Darwin published Insectivorous Plants in 1875, the first treatise to recognize the significance of carnivory in plants, after spending 16 years growing them in the greenhouse at Down House in Kent. He concluded that carnivory was convergent, having evolved independently rather than from a single common carnivorous ancestor.