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Theoretical Issues in Plant Biology

Panel Discussion

Q:  The question is about looking at the microbial diversity or looking at the differences between agricultural and non-agricultural. Jeff's thoughts?

JOHANSEN:  Yes, I have not looked at agricultural soils myself. Some people have looked at them. They tend to have completely different algae than these desert soils. One thing about agricultural soils is that they are probably the most disturbed soil you can get. If you go over some with a plow, that's probably even better than a tank. So agricultural soils tend not to have any kind of biological crusts at all. So I haven't look at those. Like you said, they've been looked at historically but I haven't looked at them.

Q:  The question is about introduction of exotic species and what the mechanism is of that introduction.

JOHANSEN:  Quite frankly, I don't know who brought over Bromus and Schismus. We could shoot them in effigy or something. Some exotics were actually introduced like there is a Tamarix pentandra that was considered to be sort of ornamental. They brought it over and it just decimated desert washes because it pulls all the water out of the wash. But those particular annual grasses may have come over with plants of other types and seeds or whatever. They're very robust.

Q:  What does the word cryptogamic mean?

JOHANSEN:  "Cryptogam" means hidden seed or hidden reproduction. So it was historically used for those plants which were the non-seed plants. So it refers to things like ferns and mosses and lichens but it also has been extended down to the fungi and the algae. It seemed like a perfect term, because there are even some of the fern allies like Selaginella in crusts. Then people said all these other things like protists and cyanobacteria are no longer cryptogams. That's when we changed the name.


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