Azolla filiculoides

Taxobox
name = "Azolla filiculoides"

---

image_width = 240px
regnum = Plantae
divisio = Pteridophyta
classis = Pteridopsida
ordo = Salviniales
familia = Azollaceae
genus = "Azolla"
species = "A. filiculoides"
binomial = "Azolla filiculoides"
binomial_authority = Lam.

"Azolla filiculoides" (Water Fern) is a species of "Azolla", native to warm temperate and tropical regions of the Americas.

It is a floating aquatic fern, with very fast growth, capable of spreading over lake surfaces to give complete coverage of the water in only a few months. Each individual plant is 1-2 cm across, green tinged pink, orange or red at the edges, branching freely, and breaking into smaller sections as it grows. It is not tolerant of cold temperatures, and in temperate regions it largely dies back in winter, surviving by means of submerged buds. Like other species of "Azolla", it can fix nitrogen from the air.

Fossil records from as recent as the last interglacials are known from several locations in Europe (Hyde "et al". 1978).

Cultivation

The species has been introduced to many regions of the Old World, grown for its nitrogen-fixing ability which can be utilized to enhance the growth rate of crops grown in water like rice, or by removal from lakes for use as green manure. It has become naturalized, sometimes also an invasive species, in several regions, including western Europe, southern Africa, tropical Asia, Australia, and New Zealand.

References

* [http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?400375 Germplasm Resources Information Network: "Azolla filiculoides"]
* [http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=200005218 Flora of North America: "Azolla filiculoides"]
* [http://plants.usda.gov/java/profile?symbol=AZFI USDA Plants Profile: "Azolla filiculoides"]
* [http://www.pfaf.org/database/plants.php?Azolla+filiculoides Plants for a Future: "Azolla filiculoides"]
*Hyde, H. A., Wade, A. E., & Harrison, S. G. (1978). Welsh Ferns. National Museum of Wales. ISBN 0-7200-0210-9.