Freshwater Algae Key Information

Instructions for using the key

• This key is not dichotomous (dichotomous keys are pased on paired choices). Instead, you are offered several choices among matching numbers or letters. Read all the key choices in each section/subsection and look at the annotated examples.


• To make a selection, click on the text next to the best description for your specimen. You can scroll through several examples at each level.


• If you hover the cursor over the text, additional information will appear (if available).


• You can scroll through small images to see examples for level above genus.


• When you reach the genus level, the images will expand to show annotations, formal taxonomic names, including the authority (person or group who published the original genus description), and collection information.


• Examine several healthy specimens before making your selection. Decomposing cells and damaged chloroplasts make identification much harder.


• Try to work with live specimens, if possible. Preserved samples are fine if you are familiar with algae, but they are more difficult to work with if you are a beginner.


• This key was developed using algae collected in northwest Washington (USA). While there will be considerable overlap with other regions, you will almost certainly encounter specimens that do not match the images in this key.

Conditions for use of the key and digital images

• This key was developed by Drs. Robin A. Matthews, Geoffrey B. Matthews, and Elizabeth A. Matthews. The authors of this key assume no responsibility or liability for any errors or omissions in the content of this site. The information contined in this site is provided on an "as is" basis with no guarantees of completeness, accuracy, usefulness, or timeliness.


• All identifications represent our best effort to provide accurate classifications using the available taxonomic literature. The nomenclature in this key follows Algaebase (Guiry and Guiry, 2023), which provides a summary of taxonomic synonyms and citations to source literature containing the diagnostic features for each taxon..


• Unless otherwise noted, all digital images in this key were photographed by Dr. R. Matthews. The images and key may be used for noncommercial purposed, with appropriate copyright acknowledgements, under the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License (CC BY-NC-SA 4.0). To view a copy of this license, visit www.creativecommons.org.


• Questions and comments should be directed to R. Matthews at desmid-dot-lady-at-gmail-dot-com

Installing this key on your computer

• Download and install the XAMPP web server: XAMPP


• Download this key as a compressed file, found here: algaekey.tar.gz


• We will attempt to keep this file up to date as changes are made to the key, but it may not include the latest changes. This compressed file was created: 6/26/2023


• Uncompress the file and place the algaekey folder into the xampp/htdocs folder.


• Instructions for decompessing tar.gz files can be found here: https://pureinfotech.com/extract-tar-gz-files-windows-10/


• Start the apache server with the XAMPP control panel.


• In your web browser navigate to localhost/algaekey