IOWA ACADEMY OF SCIENCES. 205 



20. P. perfoliatus richardsonil A. Bennett. (P.perfo- 



liatus lanceolatus Robbins.) Common in lakes and 

 quite variable; a most beautiful species. 



21. F. zostencfolius Solium. Iowa Lake. 



22. P. foliosus Raf. {P. paucifiortis Pursh.) Common 



in lakes and slow streams. 



23. P. foliosus nioijarensis (Tuck.) Morong. Swift 



running water below mill-dam, Estherville, Aug. 

 7, 1897. 



24. P. fricsii Uuprecht, {P. major (Fries) Morong.) 



Iowa Lake, and probably in other lakes through- 

 out the region. 



25. P. pecthiatiis L. Very common in lakes through- 



out this and adjoining counties. 

 Naias L. 



26. N. fiexilis (Willd.) Rost & Schmidt. Common in 



shallow water in lakes. ^ 



scheuchzeriace^. 



Triglochin L. 



27. T. marithnum L. Rare in marshes. Ours is the 



var elatum of (Iray's Manual.. 



SCHEUCHZERIA L. 



28. S. palustris L. Very rare; bog three miles north- 



west of Armstrong; the only known locality in 

 the state. 



ALISMACE^. 



Alisma L. Water-plantain. 



29. .1. plantacjo-aqiiatica L. Very common in low ground. 

 Sagittaria L. Arrow-head. 



30. S. latifolia \N\\]di. {S. r aria b His Engelm.) Frequent 



throughout but much less common than the next. 



31. S. ari folia Nutt. Very common in bogs and low 



places. This and the preceding species present 

 great variation in leaf forms. 



