You have read the heading right. It is not otherwise, not to feature the herbivory – those who graze and munch on the florid forms. Today is a specialty case. Had the nature been considered teeming with marvels, marvels above all are the plants with a preferential palate for proteins.
Today's tale will feature some killer plants. You will be told the WHYs and the HOWs behind their unorthodox way of living. Let's delve into the secret lives of carnivorous plants.
Myth vs Fact: Who are they?
It was Satyajit Roy's Septopuser Khide which introduced me with the unusual plant matters. The story was a hunter's narration of killing man-eating plants brought-up and raised by an unconventional horticulturist. Before and after this sci-fi-adventure short story, many literary works and motion pictures came out showing tentacular leafy creatures, their gory and grim way of devouring animals and humans. Yet, much different is the truth than fictitious portrayal of these 'killer' plants.
In true sense, be relaxed. Safe are you from these unique plants. Carnivorous plants are always small and delicate. You can term them in par with fragile yet exceptionally beautiful glass sculptures. The biggest prey can only be captured by the largest of the plant peers. And, that prey can only be as big as a rat. There is no such thing as Septopus from the backwater of Madagascar.
An insight to taxonomy
Carnivorous plants can be minute. But, they are diverse and risen from diverse and common plant groups. Carnivory can be seen in the group of sunflowers and daisies, so as among carnations, and even in certain grass and pineapple species. However, carnivore plants also do have their own groups, the much known sundews and pitcher plants.
Scientists thought that carnivory have evolved independently in five different groups of flowering plants. They are represented by more than a dozen genera and a staggering number of 583 species. These plants truly are carnivores – meaning they actively lure, trap, and kill the prey to absorb nutrients.
But, this is not the end. In addition, there are over 300 other plant species which show a taste in flesh secondarily. We call them protocarnivore plants.
Distribution can be termed as cosmopolitan. Except Antarctica, there is always one or two proteinaceous plants in every continent. The species diversity is most flourished in South America and Asia.
The Hunting Modes
The norm is simple. Draw an unsuspecting prey – be it a fly, mosquito or a midget, trap in a sealed enclosure, liquefy the hunt, absorb the nutrient-rich juice. Following the trapping style, five major clans can be observed. This comes particularly handy for most who don't take much fun in taxonomic jargon.
Peril in pitfalls
The users of the pitfall traps are perhaps the best known of the hunter plants. The pitcher plants are the most diverse group proliferated in the Malay Archipelago. These trappers are marked user of a pitcher-shaped growth holding an internal chamber with only one opening. Through the secretion that feign nectar, they call in insects to the chamber of death. Once the prey is secure, the secretion rapidly changes to a digestive juice. And, slowly, the poor prey transforms into a gooey substance. "The pitchers can be likened to an individual stomach" – as termed by Charles Darwin in his paramount work Insecctivorous Plants.
Few among us who don't know about glue traps that make pest stuck to a death. Well, get introduced to natural users of this mechanism – the Sundews. Luring strategy is the same, but, these plants do secure food in a different manner. Studded with mucous-secreting glands, the oval surface of sundews is equipped with tentacles. Initially, these tentacle tips broadcast food. Once the fly lands on the fleshy pad, the scenario completely alters. The sticky secretion sets in with admixture of protein-breaking enzymes. And, less than in a minute, the pad curls within – entirely trapping the meal.
The gin trappers
The iconic and the most-famous carnivorous plants put their resort to a trapping method much similar to gin-traps or traps that are activated with a trigger. The Venus Flytraps and the Waterwheel plant are the sole user of this method. Their trapping mechanism has also been described as a "mouse trap", "bear trap" or "man trap", based on their shape and rapid movement.
The traps are very similar, with leaves whose terminal section is divided into two lobes, hinged along the midrib. Trigger hairs inside trap lobes are sensitive to touch. When a trigger hair is bent, the lobes start to furl in. Osmosis regulates the inside pressures. To make the trap work with more efficacy, the lobes are embossed with long, hard setae similar to those studs of actual gin traps.
With a vacuum-pump
As the name implies, these plants hunt with vacuum forces. Seen only in one group – the Bladderworts, the bladder is a small opening, sealed by a hinged door. It draws water with rapid force once the trigger at the opening is activated. The bladderworts are aquatic, and, this way, aided with numerous bladders. It is said that a water body rich in bladderworts will never experience a bloom.
Hunting with Chai
Yes. There are plant traps which work exactly like a fish/prawn trap. Locally known as Chai – the trap made of bamboo, depicts a chamber easy to enter but the exit is topsy-turvy, either puzzling or obstructed by inward-pointed thorns. The Chai mechanism is used exclusively by the corkscrew plant from genus Genlisea. A Y-shaped modified leaf allows a prey to enter but not exit. Inward-pointing hairs force the prey to move in a particular direction. Prey entering the entrance that coils around the upper two arms of the Y are forced to move inexorably towards a stomach in the lower arm of the Y, where they are digested.
Why do they do it?
After all the ice-breaking, you are now probably wondering about the reasoning behind. Well, it is relatively easy to answer. All the carnivorous plants have originated on deficient soils. Soils that particularly poor in nitrogenous substances. So, these hunter plants still have to acquire sunlight and other stuffs. But, they, with the help of protein-breaking enzymes and symbiotic flesh-eating bacteria, suck on prey to substitute nitrates. Well-lit bog, acidic soil with clogged or running water, fen formations are the places where you can encounter one of these specialties.
Is there any in Bangladesh?
Answer to your next thought would be a big yes. Two species are so-far recorded. A Sundew from Drosera and a Bladderwort from Utricularia occurs in Bangladesh. The latter one is pretty common, it can even be found in Dhanmondi Lake. Being an aquarist and having a knack to know the otherworldly life forms, I had had the luck to collect a few stems of this aquatic species. Regarding the former, the tuber-bearing seasonal Drosera is not identified up to species level. But it is distributed in north-eastern Bangladesh, likely in hill-tracts too. One such place is Borshijora Eco-park of Moulvibazar as discovered by eminent citizen-scientist late Tania Khan.
There are speculations on more plants of this kind. The waterwheel plant of genus Aldrovendra is one such. A free-floating aquatic species and user of snap-traps, Aldrovendra is known to occur along all the major routes of migratory ducks. Our haor basin being a hotspot of a migratory flyway, Aldrovendra is likely to be there, awaiting discovery.
Of the other kinds, range of several pitcher plants overlaps forests of Sylhet and Chattogram. "There is an old record from Sylhet," stressed Dr. Monirul H. Khan, an ardent naturalist and professor of zoology at Jahangirnagar University, as I asked him on the whereabouts of the pitchers of Bangladesh. Hearing upon the response, checking the maps, and number of pitcher plants occurring in the adjacent Garo and Mizo Hills, I have gone into a trance imagining the moments of one such discovery.
Before our hilly eastern forests and her uncut gems are long gone, if this piece interests you, embark into the search for carnivorous plants! You may not find a real Septopus, but for surely, will have an exotic life like that of crazy gardener!