carnation conduction

Janice M. Glime jmglime at MTU.EDU
Mon Mar 11 20:09:53 EST 1996


Dear Plant-edders,
  We did it!  We tried an investigative lab with carnations today (and in
the prep meeting last Friday) and now I have a question.  We made our
experiments do double duty, since it should not have any significant
effect on how we interpret either set of variables.  First we cut off the
stems under water, then split the stems vertically and placed one half in
either green or blue food coloring and the other half in red food
coloring.  Then the students made a horizontal incision half way across
the stem about 2 inches above the slit and 3-4 inches below the flower and
wrapped the stem at that point with masking tape to give it support. 
Students tried to predict what color the flower would be, and so did we. 
I was wrong, and I soon realized why, but it left me with another question.
  Our results were that at first only half the flower was colored, but in
less than an hour the entire flower had the color of the dye travelling up
the uncut side.  I initially was expecting the color from the other side
to travel laterally and eventually get to the flower, but when it didn't,
I realized that the independent vascular bundles of an herbaceous plant
didn't provide any opportunity for lateral transport like we would see in
a tree.  Okay, that makes sense to me, but what happens at the flower?  I
have never seen a slide or diagram of the anatomy of the vascular tissue
at the stem/flower interface, but something unusual is going on there.  At
the leaf nodes, there was apparently no transfer of color (but I need to
recheck that since I wasn't looking for it).  How does the blue color from
the uncut side get spread throughout the many petals on all sides of the
flower if the red from the cut side cannot get across the stem, even after
three days?  Does anyone have any diagrams or know anything about the
vascular anatomy at the receptacle end of the stem?
  As an aside, we also are experimenting with aspirin, coke, and sucrose. 
Near the end of the 3-hour lab, we washed the dye off the outside of the
stems and put them in one of these solutions.  So far, control, aspirin,
and sucrose flowers (1 of each from the prep meeting) all look fine, but
the coke flower is quite wilted.  I'll tell you more when the students
finish to provide us with sufficient replication. 
Janice
***********************************
 Janice M. Glime, Professor  
 Department of Biological Sciences
 Michigan Technological University
 Houghton, MI 49931-1295
 jmglime at mtu.edu
 906-487-2546
 FAX 906-487-3167 
***********************************




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