Wednesday, August 31, 2011

Jewelweed's Ballistic Seed Dispersal Mechanism

Who hasn't enjoyed playing with jewelweed's ballistic seed dispersal system?
 Can you resist popping off a few seedpods when encountering a jewelweed patch?
Jewelweed seedpod waiting to pop

I always have to stop and squeeze a few plump seedpods...
  to see the gratifying mini explosion.
Jewelweed's ballistic seed dispersal mechanism in action
 The five outer valves of the seedpod rapidly coil,
 the columella collapses, and the seeds are launched; all in a split second.
Here is a link to a paper on the mechanics of jewelweed's explosive seed dispersal.
   The other day when I was trying to freeze (photograph) these explosive seed dispersal events, I noticed a couple of aphids and a tiny green caterpillar on a plump seedpod.  In the photo below, the caterpillar is standing straight as if it is ready for launch, but actually it is trying to hide by pretending to be a stem.  Let's just say this caterpillar doesn't realize what it is sitting on is programmed to explode.
Oh, have you ever seen a caterpillar take a rocket ride?
 Three, two, one, squeeze...
That was kinda' fun!

I was unable to follow the flight trajectory of the caterpillar, but I doubt it was harmed, just suddenly relocated.
Here is a post on violet's seed dispersal by explosion.

1 comment:

  1. Bungee jumping for caterpillars -- but without the recoil ;-)