174 Thirty-Third Annual Meeting 
Potamogeton pectinatus grows very thick and mats on the 
surface. After being exposed to the sun it becomes withered 
and brownish in color and decays, thus fouling the water. It is 
very heavy and requires much labor to remove it. ‘The growth 
becomes so dense that the fish are unable to work through it and 
it becomes a great detriment, interfering also with the circula- 
tion of the water. It apparently thrives in all ordinary depths 
in ponds and I doubt whether there is any way it can be eli- 
minated. 
The next plant in extent of growth is Anacharis canadensis, 
commonly called water weed or wyme. It is valuable, how- 
ever, as a food producer and does not grow so luxuriantly but 
that it can be handled with comparative ease if desired. It dies 
in cold weather so that unless in southern sections where the 
water remains warm the year around there is little danger of 
its proving obnoxious. ‘The leaves are hght green, small and 
pretty. I have observed young snails and other aquatic life 
clinging to it. As a rule it does not grow so heavy but that the 
fish can work about. It is said of this plant, however, that some 
years ago it was introduced in Europe by a traveler who was 
very enthusiastic over its handsome appearance and purifying 
qualities. The German Government ordered some to be placed 
in canals and attached a fine to any disturbance of it. It was 
not long, however, before it grew so thickly as to clog the canals 
to such an extent that the boats could not be navigated and now 
the government offers a reward to anyone who will devise a 
means for suppressing its growth. ‘This is similar to the intro- 
duction of the water hyacinth in the St. Johns River, Florida. 
I grow this plant freely, however, at the Washington ponds as 
the cold weather invariably kills it. In order to preserve a stock 
it is necessary to transfer a few plants to the green house before 
winter opens so there is not any danger of an over abundance 
north of Washington. The suspended roots harbor quantities of 
insect food and gold fish spawn among them. 
Probably, among the most valuable plants in all respects for 
food culture are the following: Ceratophyllum demersum, Ca- 
bomba caroliniana, Potamogeton Crispus, Potamogeton foliosus 
and Vallisneria spiralis. These are all excellent oxygenators 
and food producers. C. demersum and C. Caroliniana are es- 
