Monday, January 14, 2008

One of my obsessions during the teen-age years (one of the more socially acceptable one!) was a passion for science fiction writing. I have long ago out-grown the fascination, but a little residual memory of it catches up with my every now and again.
It also catches up with my younger son, Owen, who has love of theatre and film – one of his favourite shows is the musical version of the odd “Little Shop of Horrors”.
The unifying feature of much of the science fiction I used to read, and the slightly camp story of a nerdy florist with a problem plant, is that within both genres, flesh-eating plants are the norm.
My guess is that many of the plants that feature in this fiction are based on one or two real plants, the perennially popular Venus Fly Trap in particular.
The Venus Fly Trap comes from very swampy soils in both North and South Carolina in the United States. They are such iconic plants for botanists and gardeners alike (as well as sci-fi writers obviously!) that they are endangered in the wild.
They come from wet soils with very poor fertility, and have developed methods to obtain their nutriment needs from the environment. The “traps” are especially adapted leaves with a series of special hairs protruding from the surface. When an insect lands on the leaf, and moves across it, it springs the hairs, which act as triggers to close the leaves. The insect needs to move across a number of hairs – just one will not trigger the process_ presumably an evolutionary defence against wasting energy trying to digest dirt and dust.
The “trap” has guard hairs on the outer rim, and if the insect that triggers the hairs is too small to be nutritionally viable, the leaf will not close properly, allowing the insect to escape. Similarly, if the trap is triggered by a stone of piece of bark, the leaf seams to be able to recognize this, and it opens again after about twelve hours, and ejects the foreign object.
If the leaf traps an insect, such as a fly, the process goes into overdrive. The guard hairs, cilia they are called, hold the prey within the leaf, which closes tightly enough to be water-tight. The plant then secretes digestive juices (rather like the chemicals our own stomachs use!) which break down the soft, fleshy parts of the insect, leaving the hard exoskeleton behind. When the prey has been digested, which takes from about five to ten days, the juices are re-absorbed and the trap opens again. The dried-out skeleton is exposed to the wind and soon blows away. No-one is quite sure how the plan achieves this trick, as it obviously has no muscles or a nervous system- the best guess is that differences in fluid pressure are at work.
This is a popular plant with young men. When I worked in the retail end of the horticulture trade, we had a steady demand for these insect-eating plants from such customers. Every now and then, one of the local boarding schools would have a craze on them, and we would have lots of fifteen year olds looking to buy them.
Fortunately they are not very hard to grow as long as one or two points are kept in mind.
Firstly, these are plants from warm and moist climes, and need similar conditions to grow well, especially over summer. Ideally, they should be grown in poor, wet soil, so the best bet is to use a mix of sand and sphagnum moss. Do not add any fertilizer nor any lime, and make sure the rhizome is flush with the top of the mix. Just keeping the water in the saucer underneath the pot should keep the humidity about right.
The plants need good light and warmth, but you will need to be careful to avoid exposing them to full sun near a window as they will wilt in extreme heat, especially if they are a little dry. One solution might be to grow a plant in a terrarium, where the humidity levels will be naturally high.
These plants come from areas with cool winters, so they will need a period over winter when they can have a rest. That is simply a matter of ensuring that they are a little cooler, and the watering can be slightly less during this time too.
You cannot use a Venus Fly Trap to keep the flies under control in the house, as each plant only requires about two small flies a month. I imagine that many plants are killed by inquisitive young men feeding the plants with pieces of hamburger, fried bacon and luncheon sausage.