Fuzzy stems. Why?

Stephen Jankalski CEREOID at prodigy.net
Tue Nov 21 11:49:36 EST 2000


Enough quibbling.

Everyone knows the real answer is "WHY NOT?"

Why shouldn't plants have hairy stems?


"Monique Reed" <monique at mail.bio.tamu.edu> wrote in message
news:3A1A9145.CCC3AE5E at mail.bio.tamu.edu...
> Well, now we know what happens when they don't make botany and
> horticulture students take physics...
>
> M. Reed
>
> David Kirschtel wrote:
> >
> > Monique Reed wrote:
> >
> > > Hairs on a stem or leaves can a)provide insulation b)make the air
> > > layer around the plant more turbulent and slower-moving so water loss
> > > is less,
> >
> > I'd have to take issue with this. If the hairs a far enough apart to
> > induce turbulence then the result will be to decrease insulation and
> > increase water loss. Turbulence is a mixing phenomenon. In a fully
> > developed tubulent flow profile there is effectively zero velocity
> > gradient, the average velocity next to the surface will be the same as
> > at all distances from the surface. The innerlayer/ viscous sublayer/
> > boundary layer has been eliminated. This region of relatively stagnant
> > air near the surface is what provides the insulation. If on the other
> > hand the hairs are relative densely packed they will produce skimming
> > flow over the top of the hairs, effectively creating a new elevated
> > surface and extending the region of stagnant air around the surface of
> > the plant. This is what will increase insulation and reduce water loss -
> > the absence of turbulent flow near the surface of the plant.
> >
> >
> > ------------------------------------------------------------------------
> >       David Kirschtel * kirschte at pilot.msu.edu * 517.432.0898
> >     112 N Kedzie Lab * Mich State Univ * E Lansing, MI * 48824







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