IOWA ACADEMY OP SCIENCES. 
79 
hundreds of pistillate flowers in all stages of development were 
found. A fine series of the staminate flowers were collected. 
These, so far as observed, were restricted to a small area, 
seemingly not more than a square yard in extent, in which 
staminate flowers only were found. These were at a depth of 
about two feet, growing like the others on a mud bottom. 
Heterantliera graminea Vahl. This species is distributed 
throughout the state. It was common at Mason City, Forest 
City, Lake Edwards, Lake Okoboji, Rock Rapids, in Rock 
river, and in the Big Sioux river near Granite. 
Spirodela polyrrJiiza Schleid. Common at Forest City in Lime 
creek. 
Lemna trisulca L. Very common in Lake Edwards, and also 
found at Forest City. 
Lemna minor L. Abundant in the Big Sioux river near 
Granite, and in Rock river at Rock Rapids. 
Potamogeton natans L. Not rare in the west end of Clear 
lake. Some were in fruit, others in flower. Specimens col- 
lected in Spirit lake were finely fruited. 
Potamogeton nuttallii Cham, and Schl. This rare species, 
which has hitherto been reported in Iowa only from Muscatine 
county, was found in a small pond in northern Hancock county 
south of Forest City near the intersection of the Minneapolis & 
St. Louis railroad and the Burlington, Cedar Rapids & Northern 
railroad. It was mostly in fruit. A month later Mr. Cratty 
collected it in fine fruit at the same place. 
Potamogeton spirillus Fuck. Found with the preceding. The 
species had been reported from Muscatine and Poweshiek 
counties. It is rare. 
Potamogeton loncMtes Fuck. This was common, in fiower, in 
the Big Sioux near Granite, and in Rock river at Rock Rapids. 
The submersed leaves were abundant. 
Potamogeton amplifolius Fuck. Common in the west end of 
Clear lake, mostly in fiower. A form with narrower, nearly 
green leaves was not rare. Common and well fruited in Lake 
Okoboji and Spirit lake. Rare in Rock river at Rock Rapids. 
Potamogeton prcelongus Wnef. Rather common in Clear lake. 
Fine specimens, 8 or 10 feet long, were abundant in deep water. 
Rare in East Okoboji lake. No flowers or fruit were collected. 
Potamogeton perfoUatus L. , var. ricliardsonii A. Benner. Com- 
mon in flower in the west end of Clear lake. Very abundant 
in Okoboji lakes in flower and fruit. A form found in Spirit 
