BOTANY 358MYXOMYCETE LABORATORY

 

Internet links for slime molds: http://www.ucmp.berkeley.edu/protista/slimemolds.html

 

 

Comparison of 3 types of plasmodia

 

plasmodium

Protoplasmodium

aphanoplasmodium

phaneroplasmodium

Greek derivative

protos=first

aphanes= invisible

phaneros= visible

Relative size

microscopic

fine, transparent threads

massive and visible

Veins

none

veins not conspicuous

conspicuous

Homogeneity

homogeneous

not very granular

granular

Cyclosis

slow and irregular

regular

regular

Sporophores

singe

several

several

Taxonomic category

Liceales

Stemonitomycetidae

MyxogastromycetidaeTrichiales and Pysarales

 

TERMS

 

aphanoplasmodium

capillitium

columella

grex or slug

hypothallus

hypothallus

myxamoebae

peridium

phaneroplasmodium

plasmodium

protoplasmodium

pseudocapillitium

Pseudoplasmodium

sclerotium

sorocarp

Sporophore structure

swarm cells

sphorophore types

sporangium

aethalium

plasmodiocarp

pseudoaethalium

 

I. Movie on Slime Mold Life Cycle (may not be available)

A. Visual reinforcement of lecture on slime mold life cycle.

 

II. Phaneroplasmodium, sporangia, and sclerotia of Physarum polycephalum

 

A. Observe phaneoplasmodium in the petri dishes provided. Carefully remove the lid of the petri dish and using the LOW POWER of the compound microscope observe cyclosis (streaming of the protoplasm) which is reversible.

Got any ideas of what causes the reversible streaming?

B. Observe the petri dishes which contain a plamsodium which is either forming a sclerotium or is forming sporangia. What is unusual about the shape of the sporangia? Where are the sporangia formed? What causes the formation of the sporangia and sclerotia? Do you find sclerotia and sporangia in the same petri dish?

C. Continue to observe both petri dishes over the next few laboratories and note the changes which take place.

 

III. PREPARED SLIDES

 

A. Stemonitis

Examine prepared slides of this slime mold genus. Observe the columella, capillitium, hypothallus, spores.

Is there a peridium present? If not, was there ever a peridium present? What is the function of a capillitum? What is its origin?

B. Hemitrichia

Examine prepared slides of this slime mold genus. Observe the spores and the capillitial threads which are ornamented with spiral bands. Answer the same questions as you did for Stemonitis.

What do you think is the function of the spiral bands?

C. Dictydium cancellatum: Observe the net-like peridium (actually a pseudocapillitium) and the dictydine granules in the pseudoperidium and possibly the spore walls

 

IV. HERBARIUM SPECIMENS.

 

Observe herbarium specimens of the following genera of slime molds USING THE DISSECTING MICROSCOPE.

 

A. Ceratiomyxomycetidae

1. Observe herbarium material of Ceratiomyxa. Note the externally located spores. This is one of our most common slime molds; however because of the lack of peridium, the sporophores collapse completely when air dried.

 

B. Stemonitomycetidae

1. Stemonitis. Note the same as you did in the prepared slides of this genus. In addition, note the capillitium which ends a surface net.

2. Comatrichia. Note the same features as in Stemonitis. Does the capillitium end in a surface net in this genus?
      1. Diachea leucopodia. Observe the calcareus material on the stalk and the hypothallus.
      2. Lamproderma

C. Myxogasromycetidae

1. How does this subclass differ from the other two?

2. Differentiate the following orders in this subclass and compare them to each other as well as to the order Stemonitales.

 

a. Physarales

I. Physarum. Observe the calcareous nodules on the capillitium. Where does the chemical come from?

II. Didymium. Note the whitish powder over the surface of the peridium. The powder is composed of calcium in the form of stellate crystals.

III. Diderma. Note the 2-walled peridium.

IV. Fuligo. A common slime mold in our area. Note the aethalium.

V. Craterium.

 

b. Trichiales

I. Arcyria.

II. Metatrichia, particularly M. vesparium.

III. Hemitrichia.

IV. Trichia

 

c. Liceales
      1. Lycogala epidendrum. A common slime mold in our area which can be found growing on various woody substrates. Note the pseudoaethalium and the pseudocapillitium. You should determine how to differentiate this from an aethalium and a true capillitium. Origin of these structures differentiate the structures; however you will have to use size and attachment as a means to recognize the two by sight.
      2. Tubifera ferruginosa
      3. Dictydium cancellatum
      4. Cribaria

 

 

D. Unknowns. Several genera have been placed out for your review. You are to observe the structures as you did for those above as well as place them in their appropriate Subclass and Order.