Green Manures - Azolla
- The traditional use in SE Asia and now in Hawaii.
- http://www2.ctahr.hawaii.edu/sustainag/GreenManures/azolla.asp

Azolla mexicana C.Presl
- Description of Mexican water-fern with link to image.
- http://www.ecy.wa.gov/programs/wq/plants/plantid2/descriptions/azomex.html

Azolla filiculoides Lam.
- Description, links to images and other sites.
- http://www.hear.org/pier/azfil.htm

Azolla spp
- Their value as animal feed.
- http://www.fao.org/ag/AGA/AGAP/FRG/AFRIS/DATA/558.htm

Azolla pinnata R.Br.
- Description, links to images and other sites.
- http://www.hear.org/pier/azpin.htm

The Azolla page
- Includes comparison of A. filiculoides Lam. (subgenus Azolla) and A. pinnata var. africana (subgenus Rhizosperma)
- http://azolla.fc.ul.pt/index_ing.html

Azolla caroliniana Willd.
- Accession data, University of Connecticut.
- http://florawww.eeb.uconn.edu/acc_num/198501201.html