This is another blender particle experiment. This time I used some flock particles that try to fly towards an empty and have to choose a path around a cube. I don't render the particles themselve but use a path renderer to simulate some growing plants.
I've set the rendering of the particles to b-spline, baked the pyhsics simulation (under chache) and then animated the end value of the bspline.
you can download the blend file here
twisted torus particles
particle density volumetric material
curl noise ring