Contractile roots

[Donna Maroni]

Tony Avent wrote:

> While many that we found were quite deep, it appeared that this was due to
> sedimentation, and not to the arisaema pulling itself deeper.  In fact the
> A. franchetianum that we found on a dry dusty bank were literally almost on
> top of the ground.

I doubt that 'sedimentation' could account for the bulbs/corms moving
deeper.  More likely, bulbs/corms would be subject to the same forces that
move rocks to the surface.  As reported in one of the scientific journals
a year or two ago, experiments show that rocks move to the surface because
smaller soil particles are washed or sifted downward around the larger
rocks and gradually displace larger bodies--the rocks--upward.

How about erosion of the banks as an explanation for the A. franchetianum
bulbs being on the surface?