To celebrate the second week of learnalittle, today’s post spotlights one of my favorite things: carnivorous plants.
Although popular culture seems a bit preoccupied with the idea of man-eating plants, true carnivorous plants feed mainly on insects and microorganisms (with the occasional unfortunate amphibian for some of the bigger species). What’s more, these plants aren’t feeding in place of standard photosynthesis, but supplementing necessary nutrients – especially nitrogen – that can’t be obtained in their native highly acidic bogs or barren rocky outcroppings.
There are five main types of carnivorous plants; we’ll start with the most infamous: snap traps. This subset includes the Venus flytrap, whose big, scary mouth inspired most of the above pop culture examples. Venus flytraps possess pairs of leaf blades bordered with stiff teeth-like hairs. The insides of these mouthy leaves contain both bug-attracting sap and sensitive trigger bristles that – when jiggled by a hapless bug – cause the leaf blades to swing shut. Digestive enzymes then fill the trap's “mouth,” and soon the bug is absorbed as nitrogen rich soup.
The next group is called bladdertraps. The root-like tendrils of these trapplants are dotted with bulbous bladders. The bladders continuously pump out water, defying natural osmotic pressure (the water surrounding the plant would naturally flow into each bladder). Eventually, a vacuum develops inside an empty bladder. When an unsuspecting invertebrate bumps into one of the bladder’s lever like hairs, it opens a bladder door. Due to incredible osmotic pressure, the prey is sucked inside with the surrounding water. Soon, the creature is digested and the process starts again.
Lobster-pot traps are another aquatic carnivore. These organisms sport special y-shaped leaves through which protozoa enter a plant’s body. Escaping is far more difficult. Inside this tube-like leaf, downward facing hairs allow protozoa to venture towards a stomach-like pit, but block the way back up. Their tiny prey has no choice but to flap their flaggella until they’re digested.
Next up are flypaper traps. These plants behave like evil lint rollers, trapping insects with sticky mucilage, then digesting them with released enzymes. Some flypaper traps have subtly sticky leaves, while others secrete visible droplets of goo on tentacle-like appendages. Some members of the sundew species can even slowly move their sticky tentacles to actively catch a stationary bug.
Finally, we have the pitfall or pitcher plants. Pitcher plant leaves form a watertight basin, filled with rain and digestive enzymes or bacteria. Insects are drawn in by flower-like colors or sweet nectar; in some species, this nectar is actually drugged to prevent prey escape. Once inside the plant, the flaky wax walls of the basin prove very hard to climb. Most pitcher plants also have a lid-like appendage – occasionally thorn-lined – making escape even more difficult. Eventually, the prey drowns and is absorbed for it’s nutrients.
With the knowledge of what some plants do to survive, the next time you dig into a salad, feel lucky it’s not the other way around.