J. . NATURAL HISTORY BULLETIN. 



Ponds and margins of lakes. This species has the floating 

 leaves more crowded and of a stockier growth than P. lon- 

 chites with which it is often confounded. "The plant confines 

 itself mosth' to rather shallow water on the margin of sloughs 

 and ponds. The plants are often left exposed in the mud, in 

 which, if it does not become too dry, the roots survive and 

 produce short shoots bearing 3 to 4 leaves." — Repfcrt. 



Emmet county, rare, Cratty : Ames, infrequent, Hitchcock ; 

 Muscatine, the most common of the large-leav-ed species, 

 jReppert. 



7. P. PR.ELONGUS Wiil/en. Roem. x\rch., III., 331 (1803-5). 



Morong. Naiad. N. A., 32; Wats, and Coult., Gray's Man., 

 6th ed., 562; Upl am, Fl. Minn., 136; Arthur, Fl. Iowa, 30; 

 Beal and Wheeler, Fl. Mich., 146. 



Deep water, lakes and ponds. Jul}-, August. 



Clear Lake, Arthur ; Okoboji and Spirit Lakes, Hitchcock; 

 Iowa Lake, Cratty. 



Note. — P. liiccns Linn. Spec. PI., 126 (1753). Specimen.s without tlow- 

 ers or fruit of what appears to be this species were collected hy Professor 

 Hitchcock near Ames and are in the herbarium of the Agricultural College. 



8. P. PERFOLIATUS I^illll.^ zar. RICHARDSOMI A. BoiHCtt. 



Jour. Bot., XXVII., 25 (1889). P. lanccotatus Sm. Eng. 

 Bot., 1985 (1808), P. perfotiatus V2<x. la}iceoIatiis Rob- 

 bins in Grav's Man., 5th ed., 488 (1867). 



Morong, Naiad. N. A., 33; Wats, and Coult., Gray's Man., 

 6th ed., 562; Arthur, Cont. Fl. Iowa, V.; Upham, Fl. Minn., 

 137- 



Shallow water in lakes, ponds, and streams — ^a most beau- 

 tiful plant. Jul3^ I have not seen the tvpical P. perfoliatiis 

 from Iowa. 



Okoboji and Spirit Lakes, Hitchcock; Emmet county. 

 Cratty. 



9. P. zosTER^FOLius SckiuH. Enum. PI. Sael, I., 50 (1801), 



P. comprcssiis Fries. Nov. ed. 2, 44 (1828), non Linn. 



