Diversity = Great

Genera = 450 & Species = 7,000

Color

The colors of Chlorophyta range from Green to Orange. The orange color is due to Carotenoids which form the Accessory Pigments for this Division.

Their Photosynthetic Pigments are Similar to those of Vascular Plants.

Chlorophyll a, b are typically present along with

a, b Carotene plus Xanthophylls.

The Cell Wall is very similar to that of terrestrial plants because its main components are Cellulose & Pectins.

Some species deposit Calcium Carbonate in their walls.

Halimeda is a good example of this.

Occurrence

This Division has a larger number of Freshwater species than Marine species. Marine species tend to be larger than those found in freshwater. However, the Chlorophyta do not produce organisms that approach the size of large Kelps

A few species exist on snow fields and AlgaeAntarcticSnow.jpg (23037 bytes) Glaciers. They tend to have high concentrations of Carotenoids which are responsible for the red hue of their cells. These are called "Snow Algae". They can be found in the Rocky Mountains, the Cascades, the Arctic and Antarctic, as well as most areas where there are permanent or semi-permanent snow-fields. It would be interesting to see if they occurred on the volcanic peaks of Hawai'i.

Untroden Red Snow

Red Snow containing footprints of a Yeti named David Webb

A few species are Terrestrial.

Trentepohlia eljunque is Terrestrial

Life Modes - They are predominately autotrophs. FlagelatedCellHue.jpg (11097 bytes)

Some species form Symbioses with Lichens, Hydras & Mollusks.

Ultrastructure

They are Eukaryotes and have the "Usual Suspects" when it comes to organelles.

Some species form Cell Plates that are similar to those found in land plants.

Some species have Flagella. However, flagellated cells are usually Gametes or Spores

Chloroplasts have the typical Double Boundary Membrane.

The Thylakoids can produce Parallel Bands of Three, Irregular Stacks as well as Grana.


Chloroplasts Irregular Bands Stacking Thylakoids	Chloroplast Bands of 3 Thylakoids	Chloroplasts with Grana

Chloroplast Shape varies. The trend is towards an increase in Surface Area.

Common Chloroplasts Shapes include

Cup Filament Star Reticulate (Net) Banded

Few have the Discoid Shape of most Terrestrial Plants

Spirogyra has spiral Chloroplasts	Ulothrix has band-shaped Chloroplasts	Zygnema has Star-shaped Chloroplasts
Chalmydomonas has one cup-shaped Chloroplast	Cladophora has many small oval Chloroplasts	Mougeotia has a flat Chloroplast. The disk-like areas are Pyrenoids.

Pyrenoids occur in most species.

Starch is the major storage product. Starch is stored in the Stroma of the Chloroplast.

This is unusual for Algae. It tends to make the Chloroplasts have a lumpy appearance. Note the Chalmydomonas above.

Most Algae store starch in the Cytoplasm.


*Light Microscope Photo of Pyrenoids in Mougeotia* Chloroplast**	EM Photo of a Pyrenoid in Chlamydomonas

Morphological Diversity

There is a wide range of morphological diversity . There are Unicellular, Filamentous, Siphonous, Multicellular, Colonial, Parenchymatous, Motile, Nonmotile types.

Golenkinia a Unicellular Form Volvox is a Colonial Alga	Microthamnion is a Filamentous Alga
Coleochaete is Parenchymatous

Their Size Ranges from microns to 8m.

The Chlorophyta have been divided into several Classes by Taxonomists. There is no, one absolute classification system at this time. I will present a more traditional scheme to organize these lectures. I am not going to stress Taxonomy for these lectures. However, I will mention some of the major groups as we study their morphological and reproductive adaptations. I want you to see the major morphological and reproductive trends for this division as well as the progression of traits which could have led to the first truly land plants. Dr. Smith offers several courses which look critically at algal Taxonomy, Ecology & Physiology.

Chlorophyta-1

Dr. Celia Smith's Reef Algae Website