522 TRANS. ST. LOUIS ACAD. SCIENXE. 



Lemna tkisutx'A, L. Spec. 

 Ponds; becoming scarce. 



This species prefers still water that is filled with vegetation, wliile Spirodela is 

 found also in more open water. 



L, MINOR, L. Spec. 



Stagnant water ; infrequent. 



alismace.t:. 



Aj.isma PiiANTAGO, L. Spec. 

 Wet places; abundant. 



Sagittaria VARIABILIS, Eiigel. iu Gray, Man, 1st ed.— ^'. sa- 

 gittifoUa, L., var. variabilis, Micheli in DC. Mon. Plian. iii. i8Si. 

 In shallow water or wet places ; abundant. 



We have the three forms known as: — var. ohtiisa, (Willd.) Engel. ''I.e. 2d ed. 

 ( S. obtusa, Willd. Spec, iv.), leaves large and broad, obtuse, usually with an abrupt 

 short point, lobes broad and short, flowers dicEcious; var. latifolia, (Willd.) Engel. 

 1. c. {S. latifolia, Willd. 1. c.) , leaves rather large and broad, obtuse or usually acute, 

 lobes often longer and narrower than in the preceding, flowers moncecious ; var. has- 

 tata, (Pursh) Engel. I.e. (S. /laf/n/a, Pursh, Fl.), leaves with terminal and basal lobes 

 quite similar in size, long, narrow and acute, flowers monoecious. For notes on 

 these forms see Britton, Torr. Bull. xvii. p. 5, 1890. 



S. HETEROPHYLLA, Pursh, Fl. 



Muddj' shores of ponds ; scarce. 



Pond nortlieast of Ames, beyond Skunk river; abundant at Cairo lake. 

 S. GRAMINEA, Michx. Fl. 

 Wet places; infrequent. 



I have also found what appears to be S. cristata, Engel. in Arthur, Contr. Fl. 

 Iowa (Proc. Davenp. Acad. Sci. iv. p. 29, 1886), but more study is needed. 



XAIADACE^E. 



Triglochin maritimum, L. Spec, 



A single specimen in my herbarium collected by Mr. M. E. Wells in the "forks." 



Potamogetou fluitans, Roth. Teut. Fl. Germ. i. 1788. 



Streams around Cairo lake. 

 P. Illinoensis, Moroag in Bot. Gaz. v. 1880. 



Ponds and lakes ; infrequent. 

 P. HETEROPHYLLUS, Schreb. Spicil. Fl. Lips, 1771, 



Ponds; infrequent. 

 P. lucens, L. Spec. 



Sterile specimens, from the pond under the first railroad bridge below the gate, 

 appear to be this species. 



P. zoSTERiEFOLius, Schum. Enum. i. 1801. 



Lakes and streams; not uncommon. 

 P. obtusifolius, Merteus & Koch, Deutschl, Fl. i, 1823. 



What appears to be this species was found in the pond, under the first railroad 

 bridge, in considerable quantity, but has disappeared. 



P. pusillus, L. Spec. 



Abundant at Cairo lake. 



