264 DAVENPORT ACADEMY OK SCIENCES. 



Lemna, L. Duckweed. 



836. L. trisulca, L. 



Ponds near Cedar River ; abundant locally. 



837. L. minor, L. 



Ponds ; frequent. Found in bloom along Cedar River near 

 the B. C. R. & N. Railroad bridge, September 24, 1894. 



Wolffia, Horkel. 



838. IF. Columbiana, Karsten. 



Growing with L. trisulca, L. minor, ami Spirodela in Oep- 

 ping's Pond, near Moscow. 



839. W. Brasiliensis, Weddell. 

 Ponds ; common. 



ALISMACEiE. 

 Alisma, L. 



840. A. Plantago, L. Water Plantain. 



Shallow water and margins of ponds ; common. 

 Sagittaria, L. Arrow-head. 



841. S. variabilis, Engelm. 



Wet places ; common. The varieties, obtusa, latifolia, and 

 angustifolia are also found. 



842. 5. heterophylla, Pursh. 



Sloughs and swampy places on Muscatine Island ; not rare. 



843. £. graminea, Michx. 

 Wet places ; frequent. 



844. S. calycina, Engelm. 



In mud and shallow water along the Mississippi River. Mus- 

 catine Island. 

 Echinodorus, Richard. 



845. E. rostratus, Engelm. 



Margins of ponds, etc. Muscatine Island ; infrequent. 



NAIADACE/E. 



Potamogeton, Tourn. Pondweed. 



846. P. nutans, L. 



Ponds along Cedar River; infrequent. 



847. P. Pennsylvanicus, Cham. 



Ponds along Cedar River, June, 1894. Infrequent. 



