General
Information
How many carnivorous plants exist?
What is the biggest, most amazing carnivorous plant?
What do carnivorous plants eat?
How do I grow carnivorous plants?
People trade them – how do I get in on the action?
Where can I buy carnivorous plants?
This publication contains information on the ecology, cultivation, taxonomy, and other aspects of carnivorous plants (hereinafter CP or CPs).
The usual definition of a CP is a plant that attracts, captures, kills, and digests animal life forms. The question can also be asked: 'Why are the carnivorous plants carnivorous?'
Somewhere along the evolutionary chain and as land forms and drainage patterns changed, some plants were in peat bog situations, where the soil nutrition was very poor, and the general level of water table was fairly high. The poor nutrition availability came about because the acidic nature of their growing environment drastically reduced the rate of decomposition of dead plant material – the nutrients (particularly useable nitrogen compounds) were locked up in the non-decaying plant material, and thus unavailable to the living plants.
|
|
|
Nepenthes
|
But, in nature given the time and the need, most life forms are very resourceful and will adapt to new situations. The wet environment where these plants lived also had an abundance of various insects living there – the insects could breed well in this environment. So the plants gradually developed methods whereby they could lure or trap these insect creatures, together with the chemistry necessary to convert this resource to something they could directly use. And now we still have some of the remaining plants that performed the various types of adaptation – the ones that haven't yet become extinct because of our intervention.
The carnivorous plants use acids and enzymes in a process remarkably similar to our animal digestion, to get the life-sustaining materials they need.
As explained in the previous section, most of the nutrients in the peat bog ecosystem are locked up in the non-decaying dead plant material. It is interesting to note that this is a direct opposite of the conditions existing in the rain-forest.
In the rain-forest environment almost all of the total nutrition is in use by the living plants at any time. When some whole or portion of a plant dies there is a rapid decay of the dead material and the results are quickly absorbed by the roots of the nearby living plants.
How many carnivorous plants exist?
There are far more CPs in the world than the Venus Fly Trap. Nearly 600 species and subspecies of CPs have been described (although some are now extinct). The largest and most widespread genus is Utricularia, but many other genera exist and all known genera are described below in Section 4.
|
|
|
Venus Fly Trap
|
A taxonomical breakdown of all the different carnivorous genera has been prepared, sorted by botanical order and family, images of species from most genera are available on Rick Walker's pages in the Internet.
What is the biggest, most amazing carnivorous plant?
It depends upon your definition. In terms of sheer bulk, the largest CPs are in the genus Nepenthes – large vines up to tens of metres long. This genus also catches some of the largest prey, including creatures as large as frogs. Very rarely, captures of birds or rodents are reported, but these cases probably involved sick animals and certainly do not represent the norm. In terms of gruesome factor, the most well-known and amazing CP is probably the familiar Venus Fly Trap (VFT), which has leaf lobes that quickly capture prey dramatically. Meanwhile, the most complex and rapidly acting trap belongs to the underwater plants in the genera Aldrovanda and Utricularia. Aldrovanda vesiculosa, a relative of the VFT, may have up to a hundred traps that close on prey when touched in about two hundredths of a second. And the fascinating Utricularia species which suck prey into bladders in times as short as 1/30 of a second.
|
|
|
Nepenthes rajah
|
What do carnivorous plants eat?
Many CPs live in aquatic conditions. These plants capture very small freshwater creatures – prey like the minute rotifers and daphnia. Others may eat larger aquatic prey such as mosquito larvae. Presumably very young fish fry may be in danger. On land, Pinguicula and Drosera plants tend to catch flying insects like mosquitos, gnats, flies, and moths. Pitcher plants capture insects which forage for food, especially flies and ants.
Venus Fly Traps capture any crawling or flying creature of suitable size – they feast particularly on spiders, but plants in the wild may have a different diet. The 'Daddy-long-legs' spiders seem to have a fascination for these plants (there is no arachnid phobia of VFTs), and on many occasions the long spindly legs can be seen protruding from a closed trap.
As mentioned earlier, very occasionally vertebrates are supposedly captured, such as rats, birds, or frogs. These events are usually ascribed to Nepenthes species, the tropical pitcher plants. But these are rare surprises and do not represent normal prey.
As long as you are not the size of an insect, CPs are completely safe. The digestive acids and enzymes are extremely weak. Despite the fascinating notion of a plant which eats animals, instead of the usual other way around, what CPs do is not without precedent in the botanical world. We may know about plants like Mimosa (sensitive plants) that move when you touch them, but there are many other non-carnivorous plants that do surprising things. Some plants fire their seeds through the air. Some have moving flower parts. Some plants have venom glands attached to sharp spines. Aspen trees communicate with each other via ethylene gas. Compared to the fact that the sperm of mosses are free-swimming organisms that look and behave like animal sperm, CPs are pretty mundane.
|
|
|
Flower of Utricularia subulata
|
How do I grow carnivorous plants?
The first step in growing CPs is to read these pages, get a CP book from the library (VCPS has an extensive library of all the CP books), or subscribe to the CP mailing list and read that for a while (see the 'other sources of information' page for how to do this). Otherwise it is very likely your plants will die. You will need the proper potting medium, water, light, humidity, temperatures, and plants. As a disclaimer, it is important to note that what will work for one person may not work for another.
In southern Australia the many temperate climate CPs grow very well in an outdoor situation – as long as they are protected from strong winds, potted in appropriate composts, the pots are sitting in non-contaminated water, and a good level of humidity can be generally maintained. People also grow CPs in greenhouses or terraria. It is very likely you would have only disappointing failure if you tried to grow them in the normal soil of your garden. An outdoor bog can be a very suitable environment also – refer section on building an outdoor peat bog on the 'technical topics' page. Greenhouses are expensive, and if you know anything about construction you can save huge amounts of money by building your own – if you wish to head down this path. The most simple baptism to growing carnivores in an outdoor wind-protected situation, having long hours of unshaded sunlight.
For the person starting out into the interesting hobby of CP culture, it would be wise to concentrate initially on plants that originate from a climate similar to where you live. For instance, in Melbourne, all the Sarracenia species, Venus Fly Trap, the temperate climate Drosera species, Cephalotus, Darlingtonia, and many of the Utricularia species would be quite suitable. Later on, when you have gained more knowledge, the beauty of the Pinguicula genus can be explored. When you can provide suitable artificial environments, you then advance into the world of the Nepenthes, and other tropical wonders.
Specific cultivation techniques are given in the section that describes each genus. Consider the information merely as a set of suggestions – if the hints fail for you then try something similar but different. Experiment!
|
|
|
Venus Fly Trap - Dionaea muscipula |
It is essential to know that your plant may not be dying – the above-ground portions may just be dying off as part of its transition into a state of dormancy. Venus Fly Trap plants are easy and simple to grow when the grower provides for the basic needs of his plants. Provided the compost, lighting, water level at the base of the pot, humidity, and air circulation needs are met, the old reliable VFT will continue to amaze you with its colours and trapping activities.
Most CPs have a normal time of dormancy. Depending on the genus it might be in the winter or it might be in the summer – part of the learning process is knowing what each plant is trying to do at various times of the year.
Other than the onset of dormancy – who knows. Is it in an incorrect compost or just plain soil? Is it too wet in the cool months, or just too dry at any time? Does the water you use for the plant have harmful chemical impurities – like the Adelaide water supply, for instance. Is the plant getting too hot when exposed to direct sunlight in the summer? Is the plant not getting enough light? Is the plant being attacked by insect or fungus pests? The fungus Botrytis cinerea can be a difficult problem when there is insufficient air circulation around the plants, probably combined with the environment being too cool for the plant – a likely situation in winter. If this is the case increase the air circulation and probably give the plant a fungicidal spray such as Fongarid. Insect pests, such as scale, mealy bugs, caterpillars, aphids, spider mite, can be removed by hand, by a small rapid water jet wash, or by using an insecticidal spray (Rogor, Malathion, or Folimat are okay for most genera - however Rogor on Nepenthes may be detrimental).
A table of CP pests and recommended treatments is included on the Pests page
 |
|
Pingicula moranensis x ehlersai |
First, take satisfaction in the fact you successfully grew your plant to flowering size. Now you can attempt to pollinate the flowers. Many CPs can be easily fertilised. Many types of Drosera, Byblis, Drosophyllum, and Dionaea can be self-pollinated. This means taking pollen from the anthers and gently dabbing it on the stigma. Consult a beginning botany textbook to identify these organs. The floral structures of Pinguicula, Utricularia, Genlisea, Sarracenia, and a few other plants are peculiar – refer to a CP text like Schnell or Slack for instructions. Venus Fly Traps (VFTs) can be self-pollinated although they do not always produce seed. Furthermore, seed production often tires the plant noticeably: this is particularly noticeable with VFTs and many of the South African Drosera species – to such an extent that it may cause the death of the plant.
Some plants will not produce seed if you self-pollinate them – some Drosera and Byblis are this way. Nepenthes plants are either male or female, and so cannot be self-pollinated. In these cases, you must obtain pollen from someone else if you desire seed, or be lucky enough to own the male and the female of the plants to be used for hybrid seed production. Pollen may be available by trading with contacts on the internet. See the links page for more details
People trade them – how do I get in on the action?
As a member of VCPS; trading, selling, giving, swapping of plants with other members is a very interesting and rewarding activity to improve the contents of your CP collection. This is just one of the definite and distinct advantages of membership of a CP society.
Once people obtain the basic plants available commercially, the next stage is to obtain plants by trading. This is a very nice aspect of the CPer's hobby. You slowly develop a network of other growers within a CP society (around the globe, too, for the Internet adventurous ones) with whom you trade seeds, plants, and other propagables. Meet people through the Internet CP mailing list, or by advertising in the CP trade journals. Even old hands in the hobby, with whom you have little or no trading leverage, may be willing to sell you some things for a few dollars and postage. CPers tend to be very nice and sociable. If you read an article in a CP journal, and the person includes an address, by all means write him or her. That person will be happy to hear from you and you may develop a trading relationship.
Some trading options are now available on-line. See the links page.
Where can I buy carnivorous plants?
See the suppliers page for a listing of many Australian suppliers
There are a few nurseries that sell CPs in Australia. But remember, it is incumbent upon you to deal with firms that are reputable and do not sell illegally-obtained plants.
