Most plants create their food by photosynthesis, with minerals extracted from the soil via their roots, but some have a more sinister strategy. If the land is nutrient-poor, they supplement their diet with essential minerals from passing insects.
The Round-leafed Sundew, Drosera rotundifolia, entices the bugs in with sugary droplets, too sticky for them to escape from. (The grey specter towards the top of the photo is not the remains of a sundew onslaught. It is the exoskeleton of a dragonfly nymph, from which the dragonfly has long since emerged unscathed.)
Then the leaf tentacles close over its victim, as you can see on the right below, and the leaf absorbs the nutrients.
The round-leafed sundew above was growing on the edge of a pond in sphagnum moss, and it is green. This red one below was in a very dry area:
Most online sources talk about the red coloration as the norm, and I have not been able to work out why my pond-side ones are green. Lastly, although they may seem so alien, like normal plants they have flowers:
In another way to catch the unwary, the pitcher plant, Sarracenia purpurea, drowns them in its vase-shaped leaf:
And the Horned Bladderwort, Utricularia cornuta, has tiny bladders under the swamp water. When an insect touches the minuscule hairs on the bladders, it triggers the opening of a teensy trapdoor, engulfing the poor bug. And yet, the flowers are exquisite, giving no hint of what perils lie beneath.
PS For those who don’t know, Marmite is a dark brown salty spread made from yeast that British kids are raised on. It elicits strong pro/con reactions, and is now used by extension to describe people, as in “Boris Johnson is a Marmite politician.”
PPS The function of the red coloring of many carnivorous plants is unknown. It has been shown not to help attract insects, nor to be useful as camouflage.