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plant bio in Scotland

Janice M. Glime jmglime at MTU.EDU
Tue Dec 12 20:06:54 EST 1995


For Wilson Taylor, for inexpensive plant labs with little or no equipment, and
other labbers who may be interested:

Mosses are great for tropism experiments.  I normally grow them on an agar
medium with no glucose or other energy source but the agar itself.  Half
the petri plate can be covered with opaque paper to see all the mosses
bend one direction.  A table by the window would be sufficient.  Funaria
is probably the best because it germinates reliably and develops quickly. 
Temperatures around 30 deg C are best, as I recall, but room temperature
will do.  If you don't have access to agar, gelatin would probably work,
and absolutely sterile conditions are not essential.  Put lots of agar in
the plate - fill the bottom of the plate - because the agar will dry out
too soon otherwise. 

Sphagnum cation exchange is another easy one to do.  pH paper or a small $50
pencil pH meter is sufficient.  Mix salt solutions (.5 N CaCl2 works well,
but NaCl can be used as well).  If pH in these is compared to that in
distilled water, with and without Sphagnum, the distilled water pH will
change little with Sphagnum compared to the lowering in salt because the
distilled water offers no cations to be exchanged.

Testing for starch and oils in plant or animal tissue is easy.  Iodine for
the former and the latter makes paper transparent.  Students might compare
parts of plants as well as various grocery store foods.

Gut analysis to identify plant types and parts is interesting for the
students.  They can see what has been eaten and what has been digested. 
They might also measure the pH of the gut to see if acids are available to
help in digestion.

Pillbugs make good experimental organisms to screen for phenolics in
mosses and would probably work with other foods as well.  It is fun to see
what foods they choose and try to relate edibility to habitat.  Plants
that are very obvious in habitats where they live, like mosses on the
floor of a conifer forest, are more likely to have phenolic compounds to
ward off herbivory than inconspicuous plants in a field where food choices
abound.

I haven't tried cation exchange and pH changes with roots, but that is
worth a try.

One exercise I like to do is to give each small group of students a
different but not too different plant (for example, give each a different
conifer) and have them describe their plant so that when all these plants are
mixed together the other students can figure out which descripton matches
each plant.  One could then have students develop a key to these plants.

Someone suggested looking at the alga Closterium for Brownian movement. 
That's a common desmid and would probably show up in samples from a
variety of aquatic habitats.

I have one lab I call adaptations.  We have plants from outdoors and the
greenhouse (it's winter here at the time) scattered by groups of
adaptations on all the lab benches.  Students circulate to each bench to
examine the adaptations to various conditions.  We have a dispersal table
with moss capsules that perform on demand, horsetail elaters, fern
sporangia with annuli, and then various other plants with a variety of
seed and fruit types and protective mechanisms for their propagules.
Another table has sun/shade plants and adaptations to water. 
Insectivorous plants and ericads are used for adaptations to low
nutrients.  One table has succulents and other types of dry habitat
adaptations.  We tie these adaptations in with increasing UV light and
temperatures.

I'm not sure what level of experiments etc. you are looking for, but these
should be a start.

***********************************
 Janice M. Glime
 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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