MICHIGAN ACADEMY OF SCIENCE. 
201 
ROLE OF VEGETATION OF A 
MILL-POND. 
BY FRED A. LOEW. 
The data for this article were taken from an old mill-pond located in 
Salem township, Allegan Comity, Michigan. The dam which forms 
this pond was built about 46 years ago. The stream furnishing the 
water is small, not more than 10 or 15 feet wide and only from 8 to 
12 inches deep, with the characteristic deep holes which are found in 
streams of this character in the glacial drift of Michigan. This stream 
is called the Little Rabbit river; one of the tributaries of the Kalamazoo 
river system. 
The Little Rabbit river drains a large bog in the eastern part of Salem 
and western part of Dorr townships. This bog is of the high moor 
type; the water coming from springs, seepage and surface drainage. 
The swamp is sufficiently dry to permit of a good stand of soft maple, 
black ash and American elm. The stream flows from the northeast ; 
the water entering it from the north and west comes from a district 
of loam soil 50 to 75 feet above the river bottom. The water coming 
from the south and east drains a sandy district. The flora of the 
mill-pond has probably been derived from swamps or ponds along this 
stream. 
The flood plain where the dam is located is about 700 feet wide. The 
dam raised the water sufficiently to form a pond one mile long with 
an average width of about 700 feet and a depth of 6 feet at the dam. 
The pond is bordered by a bank from 10 to 15 feet high in places. The 
shore line is irregular. The channel which had an original depth of 6 
to 10 feet is located near the middle of the pond. The original depth 
of the pond for nearly half its length above the dam was about 5 feet. 
This whole area was covered with trees at the time it was flooded. 
Later these trees were cut leaving the stumps and refuse logs in the 
pond. (Fig. 1.) 
As above stated the channel of the original stream extends the entire 
length of the pond in a winding course with a depth of from 3 to 8 
feet. Also along the east side of the pond there are a few holes in 
which the water is from 7 to 10 feet deep. These holes are due to 
irregularities of the flood plain which have been formed by the old water 
course of the stream. 
The current in the channel is very sluggish. In all parts of the pond 
where the water is over four feet deep there are only a few growing- 
plants; a few plants of Ceratophyllum were found by dredging. 
The present condition of this pond makes it possible to divide it 
into four different plant associations which are as follows: Potamogeton 
— Ohara association; Typha — Sparganium association; Gramineae — 
Carex association and that association of plants growing on stumps 
and logs. 
The Potamogeton — Ohara (Pond-weed — Stonewort) association ex- 
tends north from the dam to about the middle of the pond, covering 
