Leaf of the Day - Day 24

I couldn't run a 'Leaf of the Day' throughout November without mentioning the most dramatic and specialised leaves that I come into contact with every day - my faithful Venus Flytrap (Dionaea muscipula).

It's been an exceptional summer for my little carnivorous chum and it's put out many new 'mouths'. At one point there were twenty and I had to re-pot it. That meant buying a special low nutrient potting compost. The Flytrap lives in poor soil in the damp bogs of North Carolina in America, which is why it ended up evolving another way of gathering essential nutrition.

To give you some idea of how well the plant did this year, here it is in November last year in its old pot.

They're a fairly low maintenance houseplant. You need to keep them damp but you should only give them rainwater as they are very pH sensitive. And they like sunshine - mine sits in the south-facing window of my study - because in their natural environment they have no tree cover. 

One other thing is that, if you want the plant to last a few years (mine is 4 now), you need to remove flowers whenever they start to develop. Unfortunately, the energy expended in flowering will often weaken the plant so much that it dies. Which is a shame as I'd quite like to see mine do this:

Image: Creative commons

Other than that, they just get on with it and they do catch the occasional insect. However, their name is something of a misnomer. In the wild, flying insects make up less than 5% of their diet. The majority comes from ants (33%), spiders (30%), beetles (10%) and grasshoppers (10%) with the remainder being 'miscellaneous'. 

One interesting fact about the Flytrap is that it can count. When potential prey crawls into the 'mouth' and makes contact with one of several hinged 'hairs', the trap goes on standby. If the prey animal then bumps into a second hair within 20 seconds, the trap closes. If it doesn't hit a second hair within 20 seconds, the trap resets. It's a clever safeguard against wasting valuable energy on a false trigger e.g. being caused by a raindrop. 

Once the trap closes, the plant then waits for a further 5 more hair strikes before it clamps firmly closed to create a seal. Digestive juices are then released and the leaf becomes a kind of stomach, slowly dissolving its prey and extracting all of the goodness over a period of several days. When all that's left are the hardest indigestible parts of the chitin exoskeleton, the trap re-opens, is reset and the remains fall out.

Surprisingly, despite being widely cultivated for sale, the Venus Flytrap has been rapidly declining in the wild with the population estimated to have decreased 93% since 1979 . It has therefore been declared an endangered species by the US Fish & Wildlife Service.

At least my little chum is doing okay here on the Chiltern Hills.