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Teacher Notes On Soil Crust Identification

Algae-

Not thick leafy stuff(no thallus)
Thin green hairs (filamentous)
Embedded into or under the sand.
Very tiny
Prokaryote (Blue-green Cyanobacteria) or Eukaryotes (Chlorophyceae)

Liverwort-

One bilobed leaf on the ground (Thallus)
Black when dry, little green leaves when wet for 20 minutes.
Try it!
Same family as Mosses (Bryophyta class Hepaticae)

Moss-

Real leaves
Leaves connected to stems
No vascular tissue (water-carrying tubes)
Sexual reproduction
Bryophyta, class Musci

 

 Lichen-

Stuck to the ground (appressed)
Thick stuff (thallus)
Symbiotic association between a fungus and an algae.
Classified by the fungus because it goes through sexual stage. Mostly Ascomycetes

 

 

A possibility is to ask the students before you give them these notes, what they believe the functions are of each of the things that they have drawn. What is the advantage of turning tiny and black? What are those little black dots? What could they be used for? Why are they so dark when dry and green when wet? What are those little tiny black lines used for? See if they have ideas for this. This is very insightful.

Reading List:

Conrad, H.S., Redfearn, P.L.(1979) How to Know the Mosses and Liverworts Wm. C Brown Company Publishers, Dubuque, Iowa

Hale, M.E. (1979) How to Know the Lichens Wm. C Brown Company Publishers, Dubuque, Iowa

Hale, M.E. and Cole, M. (1988) Lichen of California University of California Press, Berkeley.

Nash, T.H. III (1996) Lichen Biology Cambridge University Press, Cambridge

Ruef, K. (1992) The Private Eye The Private Eye Project, Seattle.

Crusts Observation:
Objective:To be able to correctly distinguish between the major soil crusts of the desert.

Place the petri dish on the ground and make your observations while standing up. Sketch the contents of the petri dish.(5pts)
Write down 4 observations of the whole dish. (1pt each)

 

 Lean over and get a better look. From a distance of about 25cm draw the contents of the petri dish(7 pts). Look for differences. Write down 4 observations about each one. (1 pt each).

 

Using some kind of magnification (loupe or stereoscope), draw with great detail each of the contents. Write 4 observations (1 pt each)