420 
cause of high water, moist-soil plants— 
millets, smartweeds, nutgrasses and the 
like—were almost nonexistent in the 
Illinois River valley. Yet stomach 
analyses revealed that seed of these 
species formed almost one-fourth of the 
uncultivated foods taken. Noting that 
thousands of ducks were feeding on ap- 
parently barren mud flats and in shallow 
water, we conjectured that these water- 
fowl were consuming seeds deposited 
from plant beds occurring there in 1936 
and 1937. 
To ascertain the validity of this con- 
Table 3.—Per cent of use, per cent of 
abundance, and index value of aquatic and 
moist-soil plants at certain lakes in the 
Illinois River valley, 1938-40. Areas in- 
cluded are listed in table 2. 
PER 
PER CENT INGES 
PLANT CENT OF Vac 
OF ABUN- 
UsE DANCE 
Rice. cuterasss.. 6: ZOROO 1593 1oa52 
Walter’s millet.....| 6.19 0.58 10.67 
INUtofassesaae care 10.85 1,23 eee 
Largeseed, nodding 
and other smart- 
WOCUSE Bee 4.44 1.09 4.07 
Japanese and wild 
millersuas Sn eel a 3.45 3.41 
Giant bur-reed.....| 0.26 0.10 2.60 
Goantail wie ee eee 15.09 Tet D9] 
Duck patat0n. 22s: 2513 2.79 0.98 
Marsh smartweed...| 6.60 (Last 0.84 
Buttonbusheen 2. oe DAG 2 1.137 | med 
Longleaf pondweed.| 3.19 5.88 0.54 
Spike rushes... . 0.16 0.34 0.47 
Wealorass#an aye yl oo, 0.02T ? 
Water hempy a. «25a 60:02 8.80 0.34 
Marsh cord grass...| 0.05 O21 0.24 
White waterlily..... 0.08 0.74 0.10 
Sago pondweed..... 0.55 S20 0.10 
River bulrush...... 0.50 26.02 0.02 
American lotus..... 0.35 23.20 0.02 
Pickerelweed....... ££: 0.01 low 
Marsh mallow...... tf; 0.01 low 
Southern naiad..... tr. 0.12 low 
Wild tice a bua. ae 0.00 0.59 v. low 
Small pondweed....| 0.00 0.05 v. low 
Longleaf 
amimahntias aes os: 0.00 0.02 v. low 
Otherplantsa. eee also nee ae 
*Other than marsh smartweed. tBecause of difficulty 
of measuring abundance of these plants, these figures are 
not accurate but represent minimum abundance. **No 
figure because of difficulty of measurement. tr.=trace. 
ab.—abundant. v.low=very low. med.—=medium. 
Ittinots Natura History SURVEY BULLETIN 
Vol. 22fArtia) 
jecture, in 1940 we collected from three 
places mud samples aggregating 18 
square feet of surface. These samples 
yielded 2,500 seeds of Cyperus erythrorht- 
zos, 2,000 seeds of C. strigosus and 550 
seeds of water hemp, Acnida tuberculata. 
No plants had grown on these mud flats 
for 3 years. We believe that our findings 
substantiate the premise that large 
quantities of seeds deposited in one year 
may be available as food in succeeding 
years in which germination is precluded 
by unfavorable environmental condi- 
tions. 
The areas of the various plant beds, 
as determined from the maps, are only 
approximate. In certain places there 
are seasonal changes in the plant com- 
munities, changes that result in error in 
calculating the abundance of the species 
Table 4.—Per cent of use, per cent of 
abundance, and index value of aquatic 
and moist-soil plants at certain lakes in 
the Illinois River valley, 1938. Areas in- 
cluded are listed in table 2. 
PER PER 
Cent | CENT | Invex 
PLANT OF ae VALUE 
ier ABUN- 
DANCE 
Rice cut-grass..228 28.46 0.73 | 39.00 
Coontail.. Fee 22h 14.20 1.68 
Nuterasses 4/2 kane tive tr. high 
Marsh smartweed...| 9.61 14.43 0.66 
Longleaf pondweed.| 5.85 | 13.48 0.43 
Buttonbushy..-.2 <3 3.49 ab. low 
Teal grass... .. 0): ee tr. med 
Water hemp.......| 2.17 tf. med 
Largeseed, nodding 
and other smart- 
WEES ANd co eee 1.63 tr. med. 
Duck potatoe aes 1.40 7.14 0.20 
Sago pondweed..... 0.89 8.81 0.10 
American lotus..... 0.38 | 28.30 0.01 
Giant bur-reed..... 0.35 tr. low 
River bulrush...... 0.30 9.97 0.03 
White waterlily..... 0.21 0.80 0.26 
Marsh cord grass...| 0.15 0.70 0.21 
Spike rushes.......| 0.05 1.04 0.05 
Pickerelweed....... 0.00 0.40 v. low 
Southern naiad..... 0.00 tr. v. low 
Mud plantain...... 0.00 tr. v. low 
Other plants (total 
of-50)\a) se ee 7.45 yi 
*Other than marsh smartweed. **No figure given 
because of difficulty of measurement. tr.=trace. 
ab.=abundant. med.=medium.  v.low=very low. — 
