PROPAGATION OF WILD-DUCK FOODS. 
13 
stocks and will soon make a dense growth. The winter buds or 
pieces of roots with tufts of leaves must be weighted to hold them 
to the bottom and enable them to take root. This may be accom- 
plished by loosely threading several plants together and tying stones 
to them, or by embedding them in balls of clay. The broken seed 
pods also may be put into clay and dropped. 
When to plant. — Where not likely to be covered by mud, the best 
time to sow the seed pods is in fall. Winter buds collected in fall 
should be kept in cold storage, and these, as well as young plants 
gathered in spring, should be set out in May or June. 
Fig. 7. — Range of wild celery. (Black spots show where it has been successfully trans- 
planted. Crosses indicate States in which it has been propagated, the exact localities 
being unknown.) 
PONDWEEDS. 
VALUE AS DUCK FOOD. 
Pond weeds (Potamogeton) compose a greater percentage of the 
food of wild ducks than wild rice and wild celery together. This is 
due to the wider distribution of pondweeds, allowing ducks to feed 
on them in winter as well as during migration and in the breeding 
season. There are no fewer than 38 species of pondweeds in the 
United States, of which at least nine (figs. 9-17) are of practically 
universal distribution. One of the number, the fennel-leaved or 
sago pondweed (P. pectinatus, fig. 17), produces upon the rootstocks 
numerous tubers (fig. 18) which are eagerly sought by certain ducks. 
This one species makes up five-eighths of the whole quantity of 
pondweeds eaten by the canvas-back and more than a fourth of the 
