20 BULLETIN 205, U. S. DEPARTMENT OF AGRICULTURE. 



USE OF THESE PLANTS. 



The three plants just mentioned are not recommended for planting 

 in waters where any other growth is desired, since they are such rank 

 growers that they are apt to take complete possession. One of them, 

 namely, coontail, has considerable value as a wild-duck food, how- 

 ever, and may be tried in waters where other plants have failed. 



Fig. 17.— Range of wigeon-grass. 



On duck farms best results will be obtained if the unit system of 

 ponds be adopted. Ducks can be turned into one pond at a time, 

 and when a pond is eaten out it may be resown, screened off, and 

 allowed to make a new crop. Under favorable conditions water- 

 weed and coontail will grow 6 inches a day. 



