The orange particles are initially close to the tree root; they are created all along the
simulation in order to compensate for the ones that are lost due to the permeability
of the membrane.
All 29987 particles own exactly the same physical properties.
Here are some close-ups of this diffusion process:
(CMAP28 WWW site: this page was created on 03/10/2002 and last updated on 04/02/2019 07:53:07 -CEST-)