| Introduction
The genus has only one species,
Dionaea muscipula, but that does not mean that the
genus is in any way dull - for this species is better known as
the Venus Fly Trap! Known by possibly billions the world over as
‘the plant the eats bugs ,this infamous plant more than lives up
to any expectation a person may have of it. Indeed, D.
muscipula is as fascinating to the CP enthusiast of thirty
years as it is to a three year old child seeing it for the first
time. D. muscipula typically grows in a rossetted
fashion, with the traps - the true leaves - held on the end of
extended leaf bases known as petioles. Whilst there are many
forms of the species, the most common of these is the typical
which is green in colour apart from the interior of the lobes of
the trap which have a red colouration when exposed to high
levels of light. It is though that this colouration within the
trap draws the attention of passing insects, luring them into
its reach.
Trap
Commonly abbreviated in CP
circles to VFT, the Venus Fly Trap has perhaps the most visually
obvious trapping mechanism of all the CPs, yet the physics
behind it as astounding as they are subtle. An insect that finds
itself in the trap will happily consume the nectar available to
it. While moving around, it is likely to touch one of the six
trigger hairs - three on each lobe - extending toward the centre
of the trap. Should the insect touch two hairs one after the
other, or touch the same one twice in quick succession, the trap
is very literally sprung. An electrical current passes through
the outside of both lobes causing the cells in these lobes to
double in length within a second. The result of this is that the
concave lobes suddenly become convex, while the spines at the
edge of the lobes intersect, producing an effective jail cell.
Contrary to popular belief, the trap does not close completely
at this early stage, and there is adequate space for any smaller
meals to slip away. This is thought to be deliberate on the
plant's behalf - there is no point in it consuming a large
amount of energy to close the trap and digest the trapped prey
if the prey will not provide a comparable amount of energy.
Assuming the prey is sufficiently
large it will not be able to escape the clutches of the trap,
and there is some evidence to suggest that the struggles of such
prey to attempt to do so are 'felt' by the plant, whose response
is to close the trap quicker! After several hours, the trap is
fully sealed and the plant begins to secrete digestive acids and
enzymes into the trap. While these are not too effective on the
hard exoskeleton of most insects, the digestive juices are more
than capable of reducing the insides of trapped prey into
nutrient-rich soup, which is readily absorbed by the plant. Once
this process has run its course, usually in around seven days,
the trap reopens leaving the exoskeleton to be washed away by
the next rainfall, ready for its next victim.
Forms
Although I have mentioned that
there is only one species in the Dionaea genus, there
are many forms. Certain forms are happy to form clumps of plants
relatively quickly, while others are slow to reproduce in this
way. On the whole growth from seed is a very slow process and it
will be around three to five years before a mature plant can be
obtained in this way.
The typical form of VFT starts
spring by producing traps on the end of short petioles, hugging
the ground in a rosetted fashion. As the summer takes hold the
petioles become longer and erect, giving the appearance that the
trap is reaching up to grab insects out of the air. More
probably is that they have evolved to do so to reach up over
scrub growth in their native habitat during the summer months.
One form, D. muscipula 'Red Rosetted', is noted for its
decumbent rosette appearance year round.
The rest of the forms can be
broadly categorised in colour and trap mutants. Coloured forms
either have especially red trap interiors, or red colour
throughout the entire plant. Such colour is difficult to obtain
in cultivation due to the high light requirements. Examples of
fully red plants are D. muscipula 'Royal Red' and
D. muscipula 'Akai Ryu'. There is also an all-green form of
D. muscipula, which lacks red pigment totally.
Trap mutants, such as D.
muscipula 'Sawtooth' or D. muscipula 'Dentate'
amongst others, have traps that differ to the typical form.
Usually, the difference is in the spines at the end of the lobes
appearing webbed. Some growers have reported dual traps - where
two traps are formed on the end of a single petiole - but these
are thought to be down to environmental conditions as opposed to
plant characteristics as this dual trap phenomenon is generally
not repeatable season to season. There has also been some talk
of an albino VFT, ghostly white in colour, but it is likely the
plant in question was very sick or the photograph itself had
been edited.
In the Wild
VFTs are very
limited in numbers in the wild, with their native populations in
North and South Carolina rapidly being drained for development.
However, the plant is very common in cultivation thanks to
tissue culture, which is starting to introduce some of the rarer
forms to a wider population also. VFTs are listed in Appendix II
of CITES, meaning they are under the possibility of future
extinction. As such, it is illegal to take plants from the wild
and export them to other countries. All VFTs for sale
internationally must have the appropriate paperwork to accompany
them, proving they were commercially raised. This is in
additional to the phytosanitary certificates required in the
export and import of most live plant material. However, if you
buy a VFT from someone in the UK and you live in the UK no
paperwork is normally needed. This is the same with VFTs on sale
in garden centres. Incidentally, if you see VFTs for sale in
garden centres with the sign asking you not to trigger the traps
artificially, please observe this. On the whole, mainstream
garden centres give the plants enough to worry about without
fingers or sticks being poked at them!
In Cultivation
Caring for VFTs in
cultivation is not too difficult, and they require no major
difference to general CP care. In the UK, most windowsills
receiving a fair degree of light will suitable for their growth.
A common VFT soil mixture is 1 part sphagnum moss peat to 1 part
sand, and they can be grown on the tray system - taking care to
ensure the water is suitable. VFTs require at least three months
of cool dormancy, and will tolerate light frosts. Once tip for
healthy VFTs is to cut away any flower scape once it is around
2cm (approximately 1 inch) high - the flowers are not very
impressive, and the plant can be weakened by flowering.
Obviously if you require VFT seeds from your plants, you'll need
to leave the plant to flower. See the Cultivation page for
further details. endorse
Further Reference
D' AMATO, P.: 'The Savage Garden' (Ten Speed
Press 1998) pp61-69
DARWIN, C.: 'Insectivorous Plants' (Langford
Press Reprint 2002) pp286-320
LLOYD, F. E.: 'The Carnivorous Plants' (Dover
Publications Reprint 1976) pp177-210
SCHNELL, D. E.: 'Carnivorous Plants of the
United States and Canada' Second Edition (Timber Press 2002)
pp81-98
SLACK, A: 'Carnivorous Plants' (Marston House
Reprint 2001) pp155-160
There many good books that have information
on these great plants.
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