Nature: April 2009

Everyone should be familiar with the genus Dionea or “Venus Fly Trap,” and you may have

previously learned of certain ant-loving Acacia shrubs, but the vegetative world is home to plenty
stranger, and while perhaps not as adrenaline-pumping as Crustaceans or as gruesome as
Amphibians, plants have more than earned the spotlight just this once, providing food, shelter and
oxygen for the entire kingdom Animalia.

Bladderwort Traps

Rather unremarkable in appearance from above, these tiny aquatic plants are actually

carnivorous, and display one of the most sophisticated mechanisms in the known plant
kingdom.

The “bladders” of the plant’s namesake are thousands of tiny, sac-like pods that hang
from submerged branches, each equipped with a hinged “door” and membranous seal
held shut by a delicate equilibrium of pressure. At the slightest touch by some tiny insect,
crustacean or even protozoa, the seal is broken and the bladder floods with water,
sucking in the prey for digestion.

Un-carnivorous Plants

Members of the genus Nepenthes are usually adapted to attract, trap and digest insect
prey in their fluid-filled “pitchers,” but Nepenthes lowii favors an alternative, even less
savory diet. The rim of its “trap” secretes a sweet, milky substance that small birds may
find both an enticing treat and fast-acting laxative; only seldomly catching insects, lowii
derives most of its sustenance as a public toilet.

Another un-carnivorous pitcher is Nepenthes ampullaria. While other pitcher traps are
shaped to keep clear of fallen leaves, twigs and other inedible detritus, this scavenging
cannibal leaves itself open to whatever might fall into its gaping gullet, actually favoring the
digestion of vegetable matter.

“Sexual Deception” in Orchid Flowers

At first glance, the flowers of many orchid species can fool even a human into seeing
some colorful bee, fly or wasp, and the resemblance is far from coincidence. Each flower
not only approximates the size, shape and color of a different local insect, but imitates the
female reproductive pheromones of the appropriate species, attracting male insects in a
certain special mood.

Whereas other flowers promise food to attract pollinators, orchids such as these take
advantage of insect mating signals to avoid the costly process of nectar production. As
the insects attempt to reproduce with the imposters, their bodies carry pollen from one
sneaky plant to the next.

A Predatory team-up

Though adapted to attract and trap insects in its sticky coating, the “paracarnivorous”
Roridula genus produces no digestive enzymes of its own, leaving the final act of
predation in the hands of a second party…

Spending their entire lives on the foliage of Roridula, the assassin bugs Pameridea
roridulae and Pameridea marlothii prey exclusively on other insects trapped by their host
plant, which in turn derives nourishment as the predators defecate. This makes Roridula
the only known plant genus that provides food for a carnivore in order to farm its own
fertilizer.

Over a meter across, the flower of this rare Malaysian plant is the single largest known to
man, and that’s only the beginning of Rafflesia arnoldii’s unusual characteristics. The rest
of the plant consists only of a fungus-like filament, which grows as a parasite exclusively
within the vines of Tetrastigma, an exotic relative of the grape. Arnoldii produces its
titanic bud di
rectly from the surface of its host, and grows for several months to bloom for
only a few days.

Often called a “corpse flower,” the odor of this monstrous blossom is notoriously
unpleasant, imitating the decaying flesh of a dead animal. Its hairy, leathery texture and
reddish coloration contribute to this illusion, attracting flies and other scavengers for
pollination. It is not known exactly how its seeds reach other Tetrastigma, but may stick to
the fur of passing rodents. Only one will be produced from each flower.