. Bulletin. Natural history; Natural history. 254 ILLINOIS NATURAL HISTORY SURVEY BULLETIN Vol. 21, Art. 8 can lotus beds in the region and drowned innumerable pecan trees in the bottoms above Beardstown. In 1938 the water level, after dropping in mid May, rose 2 to 3 feet in June and July, figs. 4-6. Such a small rise had no effect on the American lotus, fig. 13, the leaves of which rose with the water, but it left its mark on several other species. by 2 feet of water. When mapping was done in August, there was scarcely a leaf left on the plants, which were covered with sediment. They failed
. Bulletin. Natural history; Natural history. 254 ILLINOIS NATURAL HISTORY SURVEY BULLETIN Vol. 21, Art. 8 can lotus beds in the region and drowned innumerable pecan trees in the bottoms above Beardstown. In 1938 the water level, after dropping in mid May, rose 2 to 3 feet in June and July, figs. 4-6. Such a small rise had no effect on the American lotus, fig. 13, the leaves of which rose with the water, but it left its mark on several other species. by 2 feet of water. When mapping was done in August, there was scarcely a leaf left on the plants, which were covered with sediment. They failed to flower. Thus it. SCIRPUS FLUVIATILIS NELUMBO LUTEA SAGITTARIA LATIFOLIA CASTALIA TUBEROSA SALIX SPR CERATOPHYLLUM DEMERSUM POLYGONUM MUHLENBERGN POTAMOGETON AMERICANUS POTAMOGETON PECTINATUS Fig. 11.—Vegetation map of Goose Lake, showing location of principal duck tood beds, 1938. This lake is near Duck Island, a few miles south of Banner. Here semistable water levels resulted in large beds of duck potato (Sagittaria latijolia), marsh smartweed (Polygonum Muhlen- bergii) and American lotus {Nelumho luted). High water in the spring of 1938 resulted in the dis- appearance the following year of much of the duck potato bed, the areas being taken over by river bulrush (Scirpus fluviatilis), American lotus {Nelumho lulea) and coontail (Ceratophyllum demersum). Note the scarcity of longleaf and sago pondweeds {Polamogelon americanus and P. peclinalus). For instance, only a trace of sago pond- weed remained in Jack Lake in August, 1938, table 3, although in late May the lake had innumerable patches scattered over the area of several hundred acres. From the August appearance and associa- tion of the remaining patches, it was ob- vious that the greater part of the sago pondweed had been killed by the high water of June and July. Table 3 shows 210 acres of duck potato at Goose Lake in 1938, fig. 11. A survey in June revealed these plants to be covered is no wonder that only acre
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