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steam girdling

Ross Koning koning at ECSUC.CTSTATEU.EDU
Wed Jun 10 20:48:26 EST 1998


At 3:36 PM -0400 6/9/98, Jon Greenberg wrote:
>Has anyone had experience with steam girdling to kill phloem without
>mechanically injuring a plant stem? I'm working on a high school biology
>text and would like to include an activity to stress the difference
>between transport in dead xylem vesels and live phloem.
>
>I'm picturing a 250 mL flask of boiling water with a one-hole stopper
>and a piece of wide rubber tubing slit lengthwise near the end to insert
>the stem and close with a pinchcock or screwcock clamp. But will this
>work? Will the steam cool and condense too much before reaching the
>stem? Or will it jet out and scald the kids? Any thoughts or hints for
>this experiment?

Carol Reiss has something on this in her excellent lab
exercises book.  I don't have it here just now, but
think more along the line of putting a glass tube in
the end of the flexible tubing to direct the steam.  You
just point the end of the tube and hit the localized
spot on the stem you wish to treat with the steam coming
out of the tubing.  You definitely DONT want to clamp
off the tubing on a flask of boiling water...that would be
a severe safety hazard!  You don't need much steam and a
slow boil in the flask is all that is necessary to achieve
the results.

You are correct that live steam is a scalding hazard and
precautions are wise...a heavy plastic apron, gloves, and
the use of water-impermeable insulation on the tubing.
Goggles and Pyrex are important too.

ross

________________________________________________________________
Ross Koning                 | koning at ecsu.ctstateu.edu
Biology Department          | http://koning.ecsu.ctstateu.edu/
Eastern CT State University | phone: 860-465-5327
Willimantic, CT 06226 USA   | fax: 860-465-4479
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