Sarracenia Psittacena

Cephalotus Follicularious

Nepenthes Kasina

Sarracenia Alata

Sarracenia Flava (Flower)

Dionea Muscipula

Drosera Spatulata

CARNIVOROUS PLANTS: A GENERAL OVERVIEW

By COLIN LUCK Carnivorous plants are just like any other plant, but have adapted to live in specialized environments. They tend to live in poor acid soils so they have to gather their nutrients in other ways from conventional plants. To this end their leaves have evolved to serve for this application. There are many and various Carnivorous Plants world wide but they all fall into a few basic categories depending on how they trap their food supply. There is the Pitfall type trap, the sticky leaf type plant which catches its prey by allowing the insects to crawl onto the leaf and there it gets stuck, and finally the Spring Trap type. The Pitfall type trap can be subdivided into several different species, the most basic form being the Heliamphora which is considered by many to be the first of the Carnivorous plants that evolved, as it has the most basic leaf structure which is very little more than being rolled and joined along the outer edge. I’ts native habitat is South America. The next more specialized Pitfall trap is the Sarracenia which has a more highly developed leaf structure and comes in several different forms -- from the prostrate to the upright -- and each species has its own distinctive attributes. Then there is the Darlingtonia which has the common name of "Cobra Lilly" as it looks like a cobra poised ready to strike even down to two red fangs which appear to come out of its mouth. Really however it bears a striking resemblance to some form of hybrid between one of the prostrate Sarracenia and one of the Upright types. It is something like a cross between a Sarracenia Purpurea and a Sarracenia Flava with the hood of the Purpurea and the upright looks of the Flava, but because of its very specialized requirements it is in danger as it lives in areas where the roots remain cool to cold and the leaves can tolerate the higher temperature like the normal Sarracenia ,but the root conditions are completely different as the normal Sarracenia cannot tolerate the cold growing conditions of the Darlingtonia. So perhaps this is a form of adoption to allow it to survive where in other conditions it would be easily outgrown by other plants. Again both the Sarracenia and Darlingtonia are natives of the Americas. There are two more pitfall type traps which are completely different to the already discussed ones because instead of having rolled leaves they have adapted their leaves in a different manner and grow traps by extending the main rib of the leaf out into a tendril which not only serves to support the plant as these are a climbing type but can have the trap develop on the end of the tendril and pull the leaf down under its weight. These plants are found in a wide area of the world across most of the tropical areas from Madagascar in the west to Assam in the north through Malaysia and south east Asia to Queensland Australia in the south. These plants are all found in the "Old World" and have been used for many different things by the natives of these areas. An unopened pitcher contains fluid which is sterile so it can be used for an eye wash for infected eyes, through to cooking vessels in the bigger species. These where first thought of as Pipe like plants and have a hanging pitcher which attracts the prey. The traps can range in size from a few inches up to a foot across in the biggest variety. There is another interesting feature of these plants and that is the traps actually face in different directions depending on how high off the ground they are. The lower ones which tend to sit on or just above the ground face inwards towards the main section of the plant and attract crawling insects and other prey, while the higher pitchers face outwards to attract flying prey. These plants are generally found in rain forests and can climb to a height of 15 meters or 50 feet, or they can be found in open plains where they tend to grow by grabbing hold of anything available to get up off the ground. These can range from clumps of tall grasses to shrubs, but these types generally have the smaller pitchers as they attract smaller prey. The biggest Carnivorous plant or at least the biggest trap in any Carnivorous Plant is considered to be the pitcher of the Nepenthes Rajah which has been known to contain the remains of spider monkeys. These pitfall traps have a rudimentary hood over the trap to prevent it from filling up with rain water and losing all the nutrients that they have gained. Different species have different hoods and these are adaptations of where they live but remain mainly as some sought of umbrella to prevent the trap from filling up with rain water. The last type of Pitfall trap is a unique one which is only found in South West Australia in the vicinity of Albany and is called the Cephalotus follicularis or its common name the Albany Pitcher plant. This plant grows in the swamps that surround St George and has very small traps which mainly catch ants and small flies. It is the smallest of all the pitcher plants and one of the most endangered as its habitant is being constantly eroded by man’s efforts to drain the swamps and use the reclaimed land for business or residential developments. The changing weather patterns are not helping its continued existence either as the swamps that it used to thrive in may remain dry for protracted periods of time during drought conditions. The most commonly known Spring Trap is the Venus Fly Trap or as it is correctly called the Dionaea Muscipula and I don’t think that there is a single person that has not at the very least seen a picture of this plant. It again is a native of North America and is an impressive plant if only because of the rapid movement when triggered However there are many other Spring type traps although every one of these is aquatic and go under the names of Aldrovanda (The Water Wheel Plant) Utricularia (The Bladderworts) and finally Polypompholyx (The Pink Petticoats) because of the colour of their flower. The Venus Fly Trap is a fast acting trap with a leaf that has evolved into a super leaf with 3 trigger hairs on each side of the leaf. For the trap to shut two of these trigger hairs must be activated within a specific time frame and then depending on the temperature the trap will close at different speeds, the hotter it is the faster it will close. Now this trap closes in a two step manner just to make sure that it has actually got something and not a false alarm. The first stage of the closing is a loose close with the fangs overlapping to make it almost impossible for an insect to escape and the continued movement of the fly causes the trap to seal by closing around the edges and then squashing the fly. At this time digestive juices are released and the soft edible parts are consumed just like in the human stomach and when all the soft edible parts have been digested the trap opens and allows the remains to just blow away. A trap on one of these plants will generally close 3 times on its prey and about 12 times if it is triggered before the trap dies off. When it catches some prey there is a sudden increase of growth in the plant and if the weather conditions are right it will attempt to flower to reproduce. If there is a constant food supply most likely the plant will thrive during this time but otherwise it will fall back a long way in its attempt to reproduce. The Venus Fly Trap has a unremarkable small white flower head which supports several different flowers which all open at different times. The other Spring traps as previously mentioned are all aquatic so they work a bit differently and instead of having a moving leaf they have the leaf modified into what can best be described as an enclosure which develops a vacuum and there is a spring door which opens in under a thousandth of a second and sucks in its prey. Immediately that the door is sprung the leaf goes about pumping out the water that was sucked in when it last opened There are hairs of varying lengths around this door which not only help to funnel in the prey but also act as the trigger hairs to open the door. If a water dwelling insect is partly sucked in most likely the plant will suck in the whole insect as the suction increases, but occasionally the trapped insect proves to be too big for the trap and that trap dies off to prevent the whole plant becoming infected. Some of these plants while being considered as aquatic can actually grow in soil and catch small soil dwelling insects and other things that will feed it and provide the necessary nitrogen that is absent in the soil in which the plant is growing. However when these plants make the transition from water to soil the soil has to remain permanently damp/wet so the plant can survive. [Continued in next column]

Nepenthes Rafflesiana

Nepenthis Alata

Nepenthis Albo-Marginata X Veetchii

Nepenthes Dominii

Nepenthes Echinostama

Sarracenia Minor

[Carnivorous Plants: continued]

The last type of Carnivorous Plant is the sticky leaf species which all, depending on the species, have sticky leaves which trap the insect. Some actually move to better encase the trapped insect and this can be done in one of two ways. The first and most obvious is in the Sundew type plant where there are hundreds of tendrils on each leaf -- all of which grow up off the leaf and then have a sticky glutenous substance on the end. These are always highly coloured to attract both crawling and flying insects and the leaves can vary from a very small round shaped leaf of about 1/8 of an inch in diameter to long thin leaves which can be up to a meter long in some species. However normally they are around the 6 inch mark and are easily recognizable. When an insect lands or crawls onto one of these leaves to feed on the masses on the end of the tendrils, the tendrils slowly move in to allow more of them to make contact with the insect, eventually engulfing it totally together with the substance that the insect was so happily eating. The plant then starts to digest the insect and reabsorb all of the nutrients. In some of the more mobile plants of this species the leaf can fold around its victim. This substance is one of the strongest glues found in the world as it is required to trap some of the strongest insects in the world. Things like ants have a far greater lifting and carrying power per body weight than any other animal of the face of the planet. They can typically carry several times their own body weight without the slightest bit of trouble. The second type of sticky leaf plant catches its prey by allowing the insect to walk or fly onto the leaf and then begin to eat the sticky substance on the leaf which has some sort of narcotic effect on the insect and eventually traps the prey. Then the leaf slowly forms a dish under the trapped insect and pours out digestive fluids to digest the insect and absorb the nutrients. The first type is always referred to as the Sundew and the second type are generally called the Pinguicula although there are a few other species that fall into this type of trap which are the Drosophyllum and Bybliss. All of the last three types are considered as passive flypaper traps while the first the Sundew are considered as active flypaper traps. The sundew are generally speaking found all around the world in marshy areas and wet soils, but they can grow in areas which remain relatively dry provided that there is a fairly regular water supply in either the form of rain or by artificial watering systems. Some school ovals have masses of the smaller Sundew growing on them without anyone ever noticing them growing there. A general description of the actual trap structures should be added here as the Spring Traps and Sticky Leaf Traps are fairly self explanatory but the pitfall type traps are the most highly evolved on the planet. They typically have a hood covering the opening, and downward pointing hairs to lure the insects in The further down that the insects get the richer the food supply but also the harder it is to retain their footing as the traps have developed a wax like substance to clog the insects feet and the hairs all pointing the same way tend to funnel in any crawling insects to their doom. As for the flying insects, the substance that they are eating seems to have some sort of adverse affect on them as they eventually lose the ability to fly away if they stay there long enough and have not already fallen into the trap. Once they do fall in there is a wetting agent in the fluid in the trap which helps to cover the insect and it eventually drowns and sinks to the bottom of the trap or at least as far as it is possible to go with the corpses of other dead insects already in the trap. What is really interesting in all of the pitfall traps is that the fluid in them is very similar to the fluid that is in the human stomach and works much the same way. The leaf then digests or absorbs the nutrients through the inner walls of the leaf to provide food for the plant. There is one exception to this type of trap and that is in the Sarracenia Purpurea and Darlingtonia which have an enclosed hood with a small opening and what appear to be clear openings (windows) in the hood of the leaf. The insects crawl in and get confused on how to escape so they eventually fall into the fluid in the trap and in the case of flying insects can actually fly into the inside of the leaf and then fall into the fluid. Once they are actually inside the enclosed leaf there is very little chance for them to escape and they almost always eventually end up as food for the plant. The other type of pitcher plant, the Nepenthes, is more of a vine and climbs what it can find around where its seeds germinate most will quite happily eat insects and some have developed some interesting modifications to trap their prey. The Nepenthes Bicalcarata for example has two long sharp spines growing on the inside of the pitcher and it is supposed that stick insects can get their head in to feed but can not get out again so they eventually have to crawl in and die in the fluid at the bottom of the trap. With the exception of the Nepenthes Rajah every Carnivorous Plant is actually an Insectivorous Plant and not actually a Carnivorous Plant as they do not eat anything but insects. However as noted earlier in this text the Rajah has been known to take spider monkeys and though rare, their skeletons have been found inside these traps. They are really the only true Carnivorous Plant but even then they rely on passing animals for their food. While these plants may grow to great heights their traps are small in comparison to the actual size of the plant and they present absolutely no danger to humans in any form. They are nothing more than an adaptation of several plants who have found that the only place that they can compete with the other plants is in poor soils with a high acid content where most normal plants can not grow. Because of this they have evolved to suit their environment and make the most of what is available to them. While some can move parts of their leaves they are incapable of actually moving on their own accord. There has to be some outside force that causes the leaves to move around and the plants can never move from their root stock because, terrestrial plants and in aquatic plants they are at the beck and call of the water movements so they remain in a virtually undisturbed condition unless there is a strong flow of water to take part of the plant to a different location where it can grow if the conditions are right for it. If the conditions are not right for the broken off bit of the plant it dies.

Dionaea Muscipula (Venus Fly Trap)