226 



[Vol. 9, 1922] 



ANNALS OF THE MISSOURI BOTANICAL GARDEN 





Explanation of Plate 



Fig. 19 

 Fig. 20 

 Fig. 21 

 Fig. 22 



PLATE 16 



Isoetes mclanospora Engelm. Megaspores. 



7. lithophiln Pfeiffer. Megaspores. 



I. ffaccida Shuttlew. Megaspores. 



/. flaccida var. alata (Small) Pfeiffer. Megaspores 



