Listen to part of a lecture in a biology class.

(female professor)
Now, plants, like animals, and like us for that matter, need nutrients, substances that provide nourishments, to survive, thrive and grow. We get our nutrients from the food we eat. Plants, though, most plants anyway, absorb their nutrients from the soil, right, through their root systems? OK, but there are plants that don’t get their nutrients from the soil. The places they grow the soil is bad. So they get their nutrients from insects instead, from trapping and digesting insects. They are called carnivorous plants.

Carnivorous plants capture insects in different ways. They have different trapping mechanisms: active traps and passive traps. A plant with an active trap, a good example is the Venus flytrap. The Venus flytrap actually moves to capture its prey or parts of it anyway. Its leaves, it has special leaves that are hinged in the middle the two halves of the leaves open and close sort of like a mouth to catch insects. And on these leaves is a sweet nectar that attracts insects. Insects like the sweet stuff. And when they get lured in and land on the leaf , wham! The leaf springs shut. It’s an active trap. And the insect springs it so to speak. The leaf quickly closes to form a little cage, trapping the insect between the leaves. The Venus flytrap is then able to digest the insect and get its nutrients.

But other carnivorous plants, their methods are passive. They don’t have any moving parts to trap things. They have passive traps, like the sundew plant. The sundew plant also produces a sweet nectar that attracts insects. Its leaves are full of little hairs that secrete sweet substance. But what happens when insects land on sundew’s leaves to get the sweet nectar? Well, unfortunately for the insects, the hairs on the leaves also produce a super sticky glue-like substance. So an insect get stuck and can’t fly away.It basically get glued there allowing the sundew to digest it and absorb nutrients.