Book contents
- Frontmatter
- Contents
- Preface to the first edition
- Preface to the second edition
- 1 General features of the plant kingdom
- 2 The subkingdom Algae: Part 1
- 3 The subkingdom Algae: Part 2
- 4 The subkingdom Algae: Part 3
- 5 The subkingdom Embryophyta: division Bryophyta (mosses and liverworts)
- 6 The subkingdom Embryophyta (cont.): division Tracheophyta, Part 1
- 7 The subkingdom Embryophyta (cont.): division Tracheophyta, Part 2
- 8 The subkingdom Embryophyta (cont.): division Tracheophyta, Part 3
- 9 The subkingdom Embryophyta (cont.): division Tracheophyta, Part 4
- Glossary
- Suggestions for further reading
- Index
3 - The subkingdom Algae: Part 2
Published online by Cambridge University Press: 05 June 2012
- Frontmatter
- Contents
- Preface to the first edition
- Preface to the second edition
- 1 General features of the plant kingdom
- 2 The subkingdom Algae: Part 1
- 3 The subkingdom Algae: Part 2
- 4 The subkingdom Algae: Part 3
- 5 The subkingdom Embryophyta: division Bryophyta (mosses and liverworts)
- 6 The subkingdom Embryophyta (cont.): division Tracheophyta, Part 1
- 7 The subkingdom Embryophyta (cont.): division Tracheophyta, Part 2
- 8 The subkingdom Embryophyta (cont.): division Tracheophyta, Part 3
- 9 The subkingdom Embryophyta (cont.): division Tracheophyta, Part 4
- Glossary
- Suggestions for further reading
- Index
Summary
Algae containing chlorophylls a and b
In proceeding from the “chlorophyll a” to the “a + b” algae a striking difference is seen in the arrangement of the photosynthetic thylakoids. Thylakoids whose membranes contain only chlorophyll a tend to be clearly separate from each other. In the presence of chlorophyll b the apposed faces of the thylakoids are closely appressed, either generally or regionally. The stacking of the thylakoids may be in pairs or in greater numbers. This stacking of the thylakoids remains a feature of the land flora, all of which are “a+b” plants.
Prokaryotic forms
The prokaryotic algae containing chlorophylls a and b are placed in the Prochlorophyta. So far only a few examples are known and the classification is clearly tentative.
PROCHLOROPHYTA
Habitat Symbiotic, freshwater, marine.
Pigments Chlorophylls a, b; β-carotene (α- carotene in one form); zeaxanthin. Biliproteins absent.
Food reserves Starch (where known).
Cell wall components Probably cyanophyte-like.
Reproduction Presumably asexual.
Growth forms Unicellular, filamentous.
Flagella None.
Of the three prochlorophytes discovered Prochloron is the most studied. It is a unicellular extracellular symbiont of colonial ascidians of tropical and subtropical waters. The cells are 10−20μm in diameter, and divide by binary fission. The thylakoids are more or less concentric and closely stacked. A vacuole may be present, but this seems to be more in the nature of an inflated thylakoid than a discrete sac, as in eukaryotic cells.
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- Information
- Green PlantsTheir Origin and Diversity, pp. 38 - 74Publisher: Cambridge University PressPrint publication year: 2000