On the Development of Azolla filiculoides, 
Lam 
BY 
DOUGLAS HOUGHTON CAMPBELL, 
Professor of Botany in the Leland Stanford Junior University , California, US. A. 
With Plates VII, VIII, and IX, 
HE genus Azolla , though a small one, has representatives 
JL in all the divisions of the globe, except Europe, and 
here, according to Belajeff 1 , one of the American species, 
A. filiculoides, has been introduced of late years. Of the four 
species given by Strasburger 2 , two, A. filiculoides and A. caro- 
liniana , are American; A. pinnata is found in Australasia, 
Asia, and Africa ; and A. nilotica is exclusively African. 
Of the American species, A. filiculoides, the subject of the 
present paper, is confined to the western part of America, 
being reported from as far south as Chile, and reaching to 
California at least, and probably beyond. Until very recently 
American botanists confounded this species with A. caroliniana 
of eastern America, and in the Botany of California 3 only 
that species is mentioned. I have examined material from 
various parts of California, and in all cases the plants were 
undoubted specimens of A. filiculoides. Whether further 
1 Ueber das mannliche Prothallium der Rhizocarpeen ; Botanisches Central- 
blatt, 1892, No. 24. 
2 Strasburger: Ueber Azolla, Jena, 1873. 
3 Geological Survey of California. Botany, vol. ii, p. 352. 
[Annals of Botany, Vol. VII. No. XXVI. June, 1893.] 
