Fuzzy stems. Why?

Edwin Hutton e.hutton at ic.ac.uk
Wed Nov 22 05:12:50 EST 2000


Darren Obbard wrote:
> 
> (difficult to follow who said what thanks to the posting order)
> 
> > > > 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,
> 
> > > [snip: turbulence decreases boundary layers, and thus water loss
> increases]
> 
> > Well, now we know what happens when they don't make botany and
> > horticulture students take physics...
> 
> No, he was perfectly right (if I've read the order correctly),
> 
> There are 4 likely reasons for hairs on leaves/stems
> 
> 1) Hooked, barbed, poisonous, sticky or just plain awkward hairs (trichomes)
> to deter predators
> 
> 2) Denser long pale hairs to reflect light
> 
> 3) Dense hairs to extend the boundary layer (insulate) and thereby reduce
> water loss (or in some cases heat loss)
> 
> 4) Sparse hairs to increase turbulence and disrupt the boundary layer at
> lower air movement, thereby increasing water loss (and increasing cooling
> effects thereof, assuming the plant can afford to spend water on cooling )
> and increasing CO2 diffusion into the leaf (probably only relevant in dense
> stands of very fast growing material, on a still day)
> 
> Darren
> --
> Darren Obbard
> The Queen's College
> Oxford OX1 4AW

Could there be just
5) to increase the surface area (I'm not a botanist, just a thought).

Edwin Hutton






More information about the Plantbio mailing list