Type Species. Azolla filiculoides Lamarck, ranging from
Califomia to Chile.
With characters ofthe family. Chromosome number: n = 22.M/P>
A widespread genus of ten living species, no table for the symbiotic cyanobacteria inhabiting the frond-cavities, and for having among the most complex reproductive structures of any plant.
Because of its nitrogen-fixing properties, Azolla
has been cultivated for many years as a green
manure in the rice fields of southeastem Asia.
The generic name is derived from the Greek azo,
to dry + olluo, to kill, presumably because this
aquatic fem is killed by drying.
Special Literature. Svenson, H. K. 1944. The New
World species of Azolla. Amer. Fem J. 34: 69-84;
Lumpkin, T. A. i& D. L. Plucknett. 1980. Azolla: Botany,
physiology, and use as a green manure. Econ. Bot.
34: 111-153; Tryon, R. M . & A. F. Tryon. 1982. Ferns
and allied plants, pp. 776-781,13 figs.; Perkins, S. K.,
G. A. Peters, T. A. Lumpkin & H. E. Calvert. 1985.
Scanning electron microscopy of perine architecture as
a taxonomic tool in the genus Azolla Lamarck. Scanning
Electr. Micr. 1985/IV: 1719-1734, 30 figs.