The first step in identifying plants is that of direct observation of key features including colour, thallus shape and branching.

 

Let's look at colour first

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Although 3 main groups of algae exist, the range of colour varies depending on the pigments present. These pigments can also vary depending on whether the organism is submerged or exposed to sunlight. Colouration can also vary depending on the stage in the lifecycle of the organism.

 

 

Now let's look at shapes

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The main body structure of an alga is the thallus. This can come in various shapes and is essential in identifying algae. Thallus shape can range from being bladed, branched, filamentous, finger-like, spherical, stipitate to stoloniferous.

 

 

 And at branching next

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Although some may seem to have no visible branching, algae are branched in different arrangements, the main ones are shown in the diagrams below.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 And finally, other features:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 What makes identification somewhat simpler is identifying features which are unique or conspicuous such as having a dotted surface, or fanned cell rows.

 

Algae can also be observed under the microscope for structures which are not visible to the naked eye. 

 

Combining characteristics is the best method for identification of species. A key based on the identification criteria mentioned is found in the 'Activities' tab under 'Key'. This can also be accessed via the button below.