13 



MARSH CORD -QHASS, apart ina . Mi ckauxi na Hitchc. , usually 

 considered only a fair duck 'food, had -an" index rating for the four 

 areas of 0.21. We "believe this rating ^ to' he too high; seeds of this 

 species occurred in only two gizzards, vd-.ich v^'ere completely filled 

 with tlLen. ihe sampling is too. small to. give a valid index rating. 



DUCE POTATO, Sagittaria latifclia V.illd. , is regarded by 

 many hunters along the Illinois River as a good duck food plant; yet 

 the index rating of 0.20 for the four areas studied indicates that 

 it was one of the least valuable of the plants in 1958. r.iost tubers 

 of this plant examined in the field were too larg'e for ducks to con- 

 sijme; consequently, most of the food from this plant found 

 zards consisted of seeds. The, high index rating, 2.18, for the 

 Clear Lake region was due in part to a n'jmbcr of gizzards containing 

 tubers. 



SAGO POKDVvELD, F otatr.ogeton j^ ectinatus L. , a highly rated 

 duck food, had an index rating of 0.10 for the four areas. It 

 abounded at Lake Chautauqua, forming one-fifth of the vegetation. 

 In other regions it was scarce. For the Clear Lake and Chautauqua 

 region, this species had an index rating of 0.15. In the 1., 147 giz- 

 zards examined, no foliage or tubers of tuis plant v>^ere found--only 

 seeds. Seed production of tl.'is ;.^ondwoed in the Illinois River Val- 

 ley was very low in 1938, a situation that may account for the fact 

 tl'.at tills plant, usually considered an excellent source of duck food, 

 rated as one of the poorest in ti.-is region for the year. 



SPIKE RUSHES, Eleocharis spp., seemed to be cf slight 

 value as duck food in the areas studied in 1938. They had an index 

 rating of but 0.05 and were very limited in tlioir distribution. At 

 Clear Lake a fairly large bod of Eleoel aris palustris (L.) R. & S. 

 occurred. Its index rating cf 0.02 indicates that it had little 

 value as a duck food. 



RIVER BULRUSH, S cirpus fluviatilis (Torr. ) Gray, -a coarse, 

 dominant marsh plant, covered large areas in the Illinois River 

 Valley in 1938, as in most other years. Lespite its abundance, only 

 0.30 per cent of the natural food found in the duck gizzards col- 

 lected from the four areas was from this species. The indi^x rating 

 for the four areas was 0.03, indicating tiiat tiiis species is one of 

 tlie least valuable of the duck food plants. The slight value of 

 this plant is due in part to the small quantity of seed it usually 

 produces. Only occasionally does a rlvcr bulrush bed produce seed 

 \n quantity. In 1938, at Lake Chautauqua, \.hen the bulrush beds 

 pi'oduced an abundance of seed, the index rating of t}.is plant for 

 th.e area was 0.23, almost half that of longleaf pondwecd. General- 

 ly this bulrush is a weed species, competing for space with more 

 valuable food plants. 



ALIERICAi': LOTUS, N elximbo lute a (Vvilld. ) Pers., was in 1958 

 the most ab"'andant plant in the Illinois River Valley. It represented 

 28.3 per cent of the aquatic vegetation in tP.e areas considered in 

 tills paper. Yet the hard, nutlike seeds v.ere so seldom taken by 

 ducks that they totaled only 0.58 ].er cent by volume of the native 

 duck foods in the stomachs examined. Its index rating cf 0.01 indi- 

 cates that it is one of the poorest of the waterfowl food plants. 

 Since it, like river bulrush, often crov«ds out more desirable plants, 

 we must consider it a ;veed in a v.'aterfowl liabitat. 



