I. Diagnostic Characters of the Blue-green Algae.
- How many are there? about 150 genera with about 2000 species.
- How old are they? 2.8 to 2.5 billion years old with stromatolites as living fossils.
- Where are cyanobacteria found?
- Many species in freshwater habitats including thermal springs and soil.
- Many species in marine habitats as well.
- In Hawai'i, Lynbya majuscula is probably our most common marine species.
- How are their cells organized? Bacterial organization.
- What pigments do they possess?
- Chlorophyll a and phycobilins assembled as a phycobilisome on thylakoid membranes.
- How is the chloroplast constructed?
- Thylakoids do not stack at all; they form NO grana.
- There are no chloroplasts.
- What storage product is made?
- Cyanophycin starch {with alpha 1,4 linked glucans}.
- Cell wall features?
- Cells diversity and complexity is surprising for "bacteria".
- A few species remain as unicells but show no sexual reproduction.
- Aggregations of cells into "trichomes" occurs (Lyngbya).
- Filaments occur when trichomes are surrounded by a sheath.
- Cell differentiation results in "spores", akinetes and heterocysts.
- Take a look at this sampling of Cyanophytes.
II. Simple cell construction.
There is no sexual reproduction cycle know for this alga.
III. Developmental lineages.
Simple to increasingly complex (Order Chroococales).
All of these genera reproduce asexually.
Increasing complexity but single cell that produces "spores" (Order Chamaeosiphonales).
Increasingly complex morphologies (Order Nostocales) with cell differentiation into heterocysts and false branching in some genera.
All of these genera reproduce asexually
Most complex morphology result in the most advanced order, the Order Stigonematales. This group of bluegreens exhibits multicellular growth via true branching. Heterocysts still occur.
All of these genera reproduce asexually.
IV. Recap major themes.
Increasing complexity shown in morphologies and cell differentiation.
V. 
| Stromatolites, as living fossils | Archaebacteria |
| Images of Mars - early Earth environments? | Other planets for cyanophyte niches? |
| Azolla and Anabaena; Nostoc | Nitrogen fixation and history |
| Acid river for cyanophyte niche? | Local Cyanotech makes good |
| Lake Erie introduction |
This page is maintained by Celia Smith and intended for use by undergraduates and graduates, Botany Dept, Univ Hawai'i at Manoa.
