. Bulletin. Natural history; Natural history. Fig. 14.—River bulrush (Scirpus fluvialilis). This is often called flag in the Illinois River valley, where it covers thousands of acres. It is of little value as a waterfowl food plant, since it rarely produces seed. It reproduces by means of woody tubers and rootstocks. table 3, with a corresponding decrease in coontail, a more valuable duck food plant, from 99 to acres. Adjoining Beebe Lake, although lowered by the drought, averaged 8 inches deeper than Rice Lake. In Beebe Lake, coontail increased from 34 to over 418 acres, although American
. Bulletin. Natural history; Natural history. Fig. 14.—River bulrush (Scirpus fluvialilis). This is often called flag in the Illinois River valley, where it covers thousands of acres. It is of little value as a waterfowl food plant, since it rarely produces seed. It reproduces by means of woody tubers and rootstocks. table 3, with a corresponding decrease in coontail, a more valuable duck food plant, from 99 to acres. Adjoining Beebe Lake, although lowered by the drought, averaged 8 inches deeper than Rice Lake. In Beebe Lake, coontail increased from 34 to over 418 acres, although American lotus was present in much of the same area. This increase in coontail was un- doubtedly the result of shallower water, which was still not too shallow and which allowed greater bottom light intensity. Effect of Water Fluctuation The importance of fluctuating water levels as a factor affecting aquatic plants has been discussed, but the manner in which these levels directly influence vari- ous plants needs explanation. Fluctuating water levels affect aquatic plants in several ways. During flood times in spring and early summer, adequate sun- light does not penetrate sufficiently deep to enable aquatic plants to make normal growth, as in their customary depths of water. If aquatic plant beds become es- tablished in the shallows during periods. Fig. IS.—An extensive bulrush bed at Rice Lake; a few fruiting heads ot American lotus are visible. of high water, these same beds are ex- posed with the return of normal or lower levels to drying and to fermentation of the vegetative parts. This exposure not only prevents waterfowl from utilizing the plants as food, but it also usually results in failure of the plants to reproduce. As pointed out elsewhere, American lotus and river bulrush, among the less valuable waterfowl food sources, are two of the few plants tolerant of such severe physical con- Please note that these images are extracted from scanned page images that ma
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