PROPAGATION OF WILD-DUCK FOODS. 
17 
The species of ducks and swans thus far found to feed upon pond- 
weeds are the following: Sheldrake, red-breasted merganser, hooded 
merganser, mallard, black duck, Florida duck, gadwall, European 
widgeon, American widgeon, green-winged, blue-winged, and cin- 
namon teal, shoveller, pintail, wood duck, redhead, canvas-back, 
greater and lesser scaups, ring-necked duck, golden-eye, buffle-head, 
white-winged and surf scoters, ruddy duck, and whistling swan. 
DESCRIPTION OF PLANTS. 
The most important species, so far as known, is the sago pondweed 
{Potamogeton pectinatus). This plant has numerous, rather long, 
threadlike leaves, which present - 
a loose, broomlike appearance in 
the water. The plant is in some 
places known as foxtail grass. 
It is known also as eelgrass, and 
apparently is the plant termed in 
Europe poker or pochard grass, 
after a duck closely related to 
our redhead. In autumn sago 
pondweed bears small clusters of 
light-brown seeds or nutlets near 
the surface of the water, in form 
somewhat like loose bunches of 
grapes. The other pondweeds 
bear seeds in the same way, and 
vast numbers of them are eaten 
by ducks. 
The general appearance of 
sago pondweed is well shown by 
figure 17; note the brush of fine Fig. 17.— Sago pondweed. (Reduced. From 
threadlike leaves and the seed Sunset Ma * azine ' February, 1905.) 
clusters as above described. Here also are shown the tender root- 
stocks with their tubers, delicacies much sought by many ducks. 
Figure 18 illustrates the tubers natural size. 
All pondweeds of the pectinatus group have tubers, and may there- 
fore be substituted for sago pondweed for propagating purposes. 
These species are similar in general appearance and hardly dis- 
tinguishable by the layman. The scientific names and general ranges 
of the species in the pectinatus group are as follows : 
Potamogeton ftliformis Northern States, Southern Canada. 
Potamogeton interior Ontario, British Columbia, Colorado, Utah. 
Potamogeton latifolius California, Nevada. 
Potamogeton interruptus Michigan, Saskatchewan, Nebraska. 
61718°— Bull. 465—17 3 
