Our survey of plants begins with organisms which are not plants at all although they have some resemblances to plants and we may come across them when we work with plants. The Eubacteria include some photosynthetic organisms such as the cyanobacteria (which are misleadingly called "blue-green algae"). Of course all bacteria are prokaryotic whereas other kingdoms are eukaryotic. People often refer to fungi as "plants" and have mushroom growing as a branch of horticulture. However, fungi have a peculiar cell structure and many of them have chitin cell walls which makes them more like animals than plants. Fungi with cellulose cell walls are included in the Protista. Algae appear even more plant-like but are also included in the kingdom Protista. This is because they seem to be closely related to the non-photosynthetic protozoans than to true plants. Within Protista are both unicellular organisms which look like protzoans, and multicellular organisms which look more like plants.

Kingdom Eubacteria, division cyanobacteria: Oscillatoria

This is a freshwater organism which contains chlorophyll a and something like them may have been the origin of plant chloroplasts.

Pull out some filaments of these organisms from the cultures and make a wet mount on a slide. Examine under high power.

How does Oscillatoria get its name?

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Do you see any structures, like chloroplasts inside these cells?

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Are they eukaryotes or prokaryotes?

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How do you think these organisms grow?

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Kingdom Eubacteria: Rhizobium

Make a wet mount of a drop of the culture and examine under high power. What can you say about this organism?

____________________________________________________________ Have a look at the prepared slide of the legume root nodule. Where are the bacteria?

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In order to fix nitrogen the bacteria need nutrients and there must be no oxygen around. How do you think they get what they need?

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Kingdom Protista and Fungi: Pythium and mycorrhizae

Pythium is the organism that causes "damping off" of seedlings. Take some from the culture plate and look at it under high power. What is different about its cellular structure?

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Pythium has cellulose cell walls; so is it a true member of the Fungi?

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Have a look at the prepared sections of orchid root. Can you see anything that looks like Pythium, if so where?

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Is this a disease or what? ____________________________________________________________

Kingdom Protista, division chlorophyta:

These contain chlorophyll a and b (like higher plants), form starch and have polysaccharide cell walls that sometimes contain cellulose.

Chlamydomonas, Spirogyra and Volvox

These are fresh water organisms. Examine a drop of culure of each under high power.

What are the differences between each organism in terms of cellular structure?

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What differences can you see between the two organisms?

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How does Spirogrya get its name? ____________________________________________________________

Ulva or sea lettuce

This is a common marine alga which is often associated with polluted waters. The Welsh eat it for breakfast!

Examine the preserved specimen in the dish.

In what ways is it more plant-like than the other organisms you have looked at so far?

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Kingdom Protista, division phaeophyta (brown algae)

These are nearly all marine organisms which we commonly call "seaweeds". They contain chlorophyll a and c, store laminarin and have cell walls made up of cellulose and alginic acid (which is a bit like pectin).

Preserved specimens of Sargassum, Fucus and Laminaria

Look at the general morphology of these. Two structures suggest that these organisms have different habitats. Which show these structures and how do they relate to their habitat?:

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Having looked at all of these organisms, what can you say about their plant-like families?

photosynthesis	chloroplast	chlorophyll a	cellulose	non-motile	multicellular	differentiated
higher plant	+	+	+	+	+	+
Oscillatoria
Rhizobium
Pythium
Chlamydomonas
Volvax
Spirogyra
Fucus
Ulva