Re: lotus effect with Colocasia fallax

Hi Ted,

As far as I know it was the Barthlott-group in Germany who studied the Pistia-leave under SEM. They showed that the hairs are coated with wax...

David

> Date: Sun, 16 Jan 2011 16:09:12 -0500
> From: oppenhauser2001@gmail.com
> To: aroid-l@www.gizmoworks.com
> Subject: Re: [Aroid-l] lotus effect with Colocasia fallax
>
> David,
>
> I have no idea whether or not individual Pistia hairs are coated with
> some form of wax or whether the wetting by water of an individual hair
> is simply poor enough to provide a bridge for the droplet surface over
> to the next surface hair, which bridging prevents wicking of the water
> down into the hairy structure.
>
> This would be a good research topic: Dry some Pistia leaves and see
> what is extracted (meaning dissolved by some liquid, ordinarily
> followed by gentle drying to investigate the residual - Steve Lucas
> was right to insist on technical terms being defined) by solvent
> (hexane or toluene would be good solvent candidates for wax) and if it
> is indeed a waxy substance. If no one has done this I'll do it myself
> and report back to this forum.
>
> Another thing that might be of interest to aroiders is that the net
> result of Pistia hydrophobicity (which merely means its reluctance to
> be wetted by water, typically observed as a tendency for water on a
> hydrophobic surface to "bead up" into discrete droplets) is the
> extreme buoyancy of the species. Try to submerge one of these plants
> and it's almost like you are trying to submerge an air bubble. It is
> curious to me how insubstantial a Pistia leaf is. It looks big, but
> when compacted and dried there is almost nothing left. Much of the
> apparent volume is simply air.
>
> Ted Held
> Detroit.
>
> On Thu, Jan 13, 2011 at 7:53 AM, david bröderbauer
> <david_dav44@hotmail.com> wrote:
> > Hi Ted,
> >
> > Pistia is in fact a very beautiful example for a water-repellent surface. It
> > has to be kept in mind - as you mention - that it generates this
> > superhydrophobic effect with hairs (not with papillate cells like in Nelumbo
> > or Colocasia) that are covered with wax. So, the term 'lotus-effect'
> > describes the syndrom of superhydrophobicity (which means that the contact
> > angle of a water droplet is at least 150°), but there are different
> > structures within the Araceae and other plant families, that produce this
> > effect.
> >
> > David Broederbauer
> >
> >> Date: Wed, 12 Jan 2011 13:04:17 -0500
> >> From: oppenhauser2001@gmail.com
> >> To: aroid-l@www.gizmoworks.com
> >> Subject: Re: [Aroid-l] lotus effect with Colocasia fallax
> >>
> >> Geneviève,
> >>
> >> The lotus effect is quite common in my experience. It has been getting
> >> a lot of attention in the popular press lately and there are a number
> >> of academic studies of the phenomenon using nano materials. A Google
> >> search will turn up many hits.
> >>
> >> One of the best displays can be seen on the humble aroid Pistia.
> >> Leaves of Pistia will support quite a large water droplet with no
> >> wetting of the leaf surface that supports the hairs.
> >>
> >> Ted Held.
> >> Detroit
> >>
> >> 2011/1/11 Geneviève Ferry <jpcferry2@wanadoo.fr>:
> >> > Dear aroiders ,
> >> >
> >> > Today, three students came looking leaves Colocasia fallax to understand
> >> > the
> >> > phenomenon of superhydrobicity (lotus effect).
> >> > Do you have information on this phenomenon?
> >> > (Experience, etc. ....)
> >> >
> >> > Thank you for your help.
> >> >
> >> > Best wishes ,
> >> >
> >> > Geneviève Ferry
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> >> >
> >> >
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