Fig. 13: Azolla caroliniana: all greatly magnified, a, habit, upper surface of sterile 

 plant; b, lower surface, plant with microsporocarps; c, microsporocarp; d, micro- 

 sporangium with massula being discharged; e, glochida types from a single massula; 

 f, one branched glochidium: g, tip of glochidium highly magnified; h, the two-lobed 

 leaf. (From R. K. Godfrey et al. Am. Fern Journ., Vol. 51, p. 90, 1961). 



