I'm fascinated by carnivorous plants. The idea of a plant relying on protein for survival instead of the typical sun, soil and rain formula that most vegetation abides by makes them seem far more animalistic than typical flora.
On the other hand, many of these plants are simply gorgeous, like the Byblis seen above. While most carnivorous plants lure the insects inside their flowers to be slowly digested, the leaves of the Byblis are the covered in tiny, sticky hairs that secrete a mucus that attracts flying insects. Once the insects step on the sticky petals, they can't escape and slowly starve to death while the plant slowly digests them.
Environmental Graffiti has a great collection of 10 stunning carnivorous plants that's definitely worth a look.
[Image courtesy of h3_six's Flickr stream.]