ELEVEN IMPORTANT WILD-DUCK FOODS. 17 



taken at the same time and place was 84 per cent wigeon-grass; and 

 the stomach of a redhead contained about 5,120 seeds. 



Most of the duck stomachs received by the Biological Survey from 

 South Island, South Carolina, have contained wigeon-grass. It com- 

 posed 41 per cent of the food of 3 blue-winged teals collected therein 

 March, and 27 per cent of that of 8 gadwells obtained in February 

 and March. In Currituck Sound, North Carolina, wigeon-grass grows 

 among too great a profusion of other valuable duck foods to have the 

 importance attained in less favored localities; nevertheless, it is a plant 

 of considerable value. Practically 10 per cent of the food of 35 big 

 bluebills collected there in November was composed of wigeon-grass, 

 as was about the same proportion of the diet of 70 little bluebills. 



At Back Bay, Virginia, 17 per cent of the food of 9 pintails collected 

 in February consisted of wigeon-grass, and at Virginia City, Va., 16 

 per cent of the food of 14 mallards taken in January was of the same 

 composition. 



Other ducks found feeding on wigeon-grass are the Florida duck, 

 black duck, green-winged and cinnamon teals, spoonbill, canvasback, 

 ringneck, bufnehead, old squaw, ruddy duck, surf scoter, and hooded 

 merganser. 



DESCRIPTION OF PLANT. 



Wigeon-grass (Ruppia maritima) is similar in habit to sago pond- 

 weed or foxtail. 1 Both have long, slender, filamentous leaves on 

 widely spreading, much-branched stems. In wigeon-grass the basal 

 parts of many of the leaves are enlarged (fig. 15), and this, upon 

 close inspection, gives the plant quite a different appearance from 

 sago pondweed. The seeds of sago pondweed are compactly grouped 

 on a central axis, while those of wigeon-grass are borne singly on 

 rather long stalks which radiate from the top of the fruiting peduncle 

 (fig. 16). The latter organ usually is spirally coiled in wigeon-grass; 

 in sago pondweed it never has more than a simple curve. The 

 rootstock of wigeon-grass is tougher than that of sago pondweed, 

 more frequently jointed, and often angled at the joints. There are 

 no tubers. The seeds are black, rounded triangular in outline, with 

 . a small pit on each side near the apex, and on one edge an oblong lid 

 which is forced out during germination. Pondweed seeds have a simi- 

 lar lid, but are usually larger than those of wigeon-grass, never black, 

 and lack the apical pits. 



Wigeon-grass is usually referred to in books as sea- or ditch-grass; 

 it is also called tassel-grass, tassel-weed, tassel-pondweed, nigger-wool, 

 puldoo-grass, and peter-grass. The last two names are compounded 

 from terms by which the coot is known in southern States, and indi- 

 cate that wigeon-grass is highly relished by that bird. 



1 Described in Biological Survey Circular No. 81, pp. 12-16. 



