130 NYROCA VALISINERIA 



numerous straight parallel, lengthwise veins; besides these there are one median and 

 two prominent lateral veins, connected at intervals by irregular cross-veinlets. It 

 looks somewhat like Zostera or eel-grass, but differs by having the leaves grow in 

 bundles from the root-stalks while those of the eel-grass arise singly and alternate on 

 opposite sides of the stem. Pipe-wort (Eriocaulon) has ribbon-like leaves but may be 

 recognized by its reticulation into small cells of uniform size. At certain stages the 

 arrow-heads (Sagittaria) are difficult to tell from wild celery, although they usually 

 have the end of the leaf expanded into a proper leaf-blade, or else quite pointed, 

 neither of which characteristics is found in Vallisneria. The seed-pod of the wild 

 celery, into which the pollenized flower develops, is three to six inches long, and is 

 attached to the plant by a long slender twisted stem. The pods contain about fifty 

 seeds to the inch and these fall off and become embedded in the mud. This plant 

 has an irregular distribution, from Minnesota through the Great Lakes region to 

 Nova Scotia, and from eastern Kansas and eastern Texas to the Atlantic coast. It is 

 poorly represented all over New England. It can be transplanted either by the seed- 

 pods, by the so-called winter buds, or by moving the plant itself. It grows best on 

 rather firm muddy bottom in three and a half to six and a half feet of water and is 

 seldom found in thick beds unless there is a slow current. Occasionally I have seen 

 it growing on coarse sand with scarcely any admixture of mud. It never seems to 

 attain its greatest luxuriance in an ordinary inland pond where the water is not 

 moving. 



About one-quarter of the food of the Canvas-back is said to consist of Vallisneria 

 and it is usually maintained that the quality of the flesh depends entirely on this 

 plant. Certainly the finest birds come from regions where wild celery is most com- 

 mon. Canvas-backs feed especially on the root-stalks and winter buds, while other 

 species are content with the leaves and stems. 



The most important studies of the food habits of the Canvas-back are still un- 

 published, but through the kindness of Dr. E. W. Nelson of our Biological Survey I 

 am able to summarize the results. The stomachs used in the analysis numbered 

 381 and were collected during winter and early spring mostly in our southern States. 

 Triumph (Louisiana) , Lake Surprise (Texas) , Marquette (Wisconsin) , and the Missis- 

 sippi Delta contributed most of them. Taking the series as a whole, vegetable food 

 formed 84.8%, and this will be mentioned in a little more detail presently. But it 

 must not be forgotten that each locality represented furnished a special food so 

 that the final averages are not true for the winter range as a whole. For instance, 103 

 out of 1 13 birds from Triumph, Louisiana, fed very largely on the tubers of delta duck- 

 potato which averaged over 66% of their food. Ninety-five of these 113 birds had 

 taken a small snail (Neritina) to the extent of 19.43% of their diet. The banana 

 water-lily was the most important December food from Lake Surprise for it com- 

 prised over 76% of the whole. 



