58 



Spirodela, Schleid. 



polyrhiza, (L.), Schleid. {Lemiia polyrhiza, L.) 

 Wolffia, Horkel. 



Columbiana, Karst. 



ALISMACEJE. 

 Alisma, L. 



Plantago, L., var. triviale, (Pursh). {var. Americanum, Gray.) 

 Sagittaria, L. 



calycina, Engelm. 



var. spongiosa, Engelm. 

 graminea, Michx. 

 heterophylla, Pursh. 

 subulata, (Pursh). {/S. pusilla, JVuft.) 

 variabilis, Engelm., var. angustifolia, Engelm. 

 var. diversifolia, Engelm. 

 var. gracilis, (Puish), Engelm. 

 var. hastata, (Pursh), Engelm. 

 var. latifolia, (Willd.), Engelm. 

 var. obtasa, (Willd.), Engelm. 

 var. pubescens, (Muhl.), Engelm. 



NAIADACE^. 

 Triglochin, L. 



maiitimum, L. 



palustre, L. 

 8cheuchzeria, L. 



palustris, L. 

 Potamogeton, L. 



amplifolius, Tuck. 



compressup, L. 



crispus, L. 



fluitans, Roth. (P. lonchites, Tuck.) 



gramineus, L. {Includes var. graminifolms, Fries, and var. 

 heterophyllus, Fries.) 

 vai". maximus, Moron g. 

 var.(?) myriophyllus, Robbins. 



hybridus, Michx. 



lucens, L. 



natans, L. 



Oakesianus, Robbins. 



obtusifolius, Mart. & Koch. 



pauciflorus, Pursh. 



