806 Wisconsin Academy of Sciences, Arts, and Letters . 
Naiadace^e. Pondweed Family. 
33. Potamogeton natans, L. The common name Pondweed 
is applied to all the species. 
Frequent; in shallow water border of streams and 
in sluggish lakes. 
34. Potamogeton perfoliatus, L., var. Pichardsonii, A. Ben¬ 
nett. 
Frequent; same habitat as the preceding. 
35. Potamogeton zosteraefolius Schum. 
Frequent; same habitat as Po. 33. Pot named in 
Swezey’s list. 
36. Potamogeton pectinatus, L. 
Frequent; same habitat as Po. 33. 
37. Triglochin palustris, L. This and )the following are 
commonly called Arrow-Grass. 
Occasional; in wet sand, beach of Lake Michigan, 
and moist depressions on the open prairie. 
38. Triglochin maritima, L. 
Pare; two individuals gotten on edge of sedge marsh 
on Pacine prairie; the only station. Reported in 
Swezey’s list as occurring at Pacine on authority of 
Dr. Hoy. 
Alismace.e. Water Plantain Family. 
39. Alisma Plants go, L. Water Plantain. 
Common; shallow water of ditches and sluggish 
streams. 
40. Sagittaria latifolia, Willd. (S. variabilis, Engelm.) 
Arrow-head. 
Common; shallow water and borders of ponds and 
streams. Extremely variable as to foliage. A form 
with extremely narrow linear blades and basal lobes is 
frequent. I 
41. Sagittaria heterophylla, Pursh. (S. rigida, Pursh.) 
Pare; occurring in company with the preceding at 
Horlicksville, Pacine Co., though much less abundant 
than the latter species; the only station. 
