Saturday, May 7, 2011

How the windows on a Cobra Lilly actually work!

The Cobra Lilly (Darlingtonia californica) is a truly unique plant endemic to the western United States of America (northern California and Oregon). It is closely allied to the Sarracenia pitcher plants, with both belonging to the same family (Sarraecniaceae). What makes it unique is its pitcher lid, which has been modified into a large, hollow hood. The opening is underneath the hood, immediately behind a spectacular fish-tail or forked-tongue structure. Looking at the pitcher from the front, it bears a striking similarity to a cobra reared up to strike.

The top of the hood is covered in many small windows that are almost clear (not white, like those of a Sarracenia minor for example). These windows are believed to serve a special function: disorientate insects once they enter the hood so they (i.) don't escape and (ii.) are more likely to tumble into the pitcher.

But do the windows actually work? I was out with the camera a few weeks back and happened to see a Polistine paper wasp trapped inside the hood. The below .gif animation is the result of photos taken at nearly 4 frames per second.

They windows do indeed seem to disorientate insects once they are inside the hood! I was first aware that something was inside the Darlingtonia pitcher because I could hear the scrabbling of it trying to escape. These photos clearly show the wasp trying to scrabble free of the pitcher through the hood where it is most strongly illuminated by the windows. However, in this instance, the wasp was a little too big, and it eventually managed to reverse out of the hole and escaped. You can see the wings of the wasp protrude from the mouth of the pitcher if you look closely.

I will take some decent photos of my Darlingtonia setup shortly and describe completely how I grow and propogate them.