Basic Plant Phys questions

Charles Kraft ckraft at
Mon Nov 30 23:31:22 EST 1998

Moonlight has the same spectrum as daylight, as evidenced by taking
photographs under moodlight.  Color is distorted somewhat by film
failure, but is generally accurate.

Poinsettas in  California outdoors also bloom, the idea of keeping
them in the dark is to control the timing of blooming.  They sell well
for Christmas, not so well for President's Day.


On 29 Nov 1998 09:39:06 -0800, jmglime at MTU.EDU ("Janice M. Glime")

>Hmm...  Keeping Poinsettias in total darkness is probably only because
>places where humans grow poinsettias are usually subject to human
>intervention with the light - street lights, house lights, etc.  I know
>that one street light will keep them from blooming, but total darkness
>does not exist in their native habitats - they are not under snow for
>months.  In Florida they bloom, and the moon shines there.  It is
>reasonable to assume that the red light of our artificial light is the
>source of the problem, but that moonlight is not.
>Does anyone know the actual spectrum of moonlight?  Is the lack of color
>simply its inability to stimulate our cones due to low intensity, or is
>there really an altered spectrum?
> Janice M. Glime, Professor  
> Department of Biological Sciences
> Michigan Technological University
> Houghton, MI 49931-1295
> jmglime at
> 906-487-2546
> FAX 906-487-3167 

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