152 ILLINOIS ACADEMY OF SCIENCE 
6. Persicaria pennsylvanicum (L.) Small. Pennsylvanica 
Persicaria. 
Rather common and varying considerably in size, but all the 
plants markedly dwarfed. Several were greatly reduced, 
one with only two leaves and a single flower. Britton & 
Brown give the size as “1-3 tall.” Robinson & Fernald do 
not mention the size. 
7. Acnida tuberculata Moq. Rough-fruited water-hemp. 
Like many other plants along the shores of the Mississippi, 
this species varies greatly in abundance from year to year, in 
favorable years being exceedingly abundant and in unfavor- 
able years rather scarce. It is pretty closely confined to the 
stretch of shore between the base of the fringe of willows that 
mark the normal high-water line, and the low-water line. Dur- 
ing the summer of 1910, a period of prevailing low water, the 
mud flats along the sloughs were left uncovered most of the 
summer, and great stretches were densely overgrown with this 
species. It is indeed one of the most remarkably variable, even 
under conditions of normal growth, of all our plants, many of 
the individuals being tall and erect, much resembling the com- 
mon rough pigweed (Amaranthus) others prostrate, many 
with the flower clusters interrupted, others with these continu- 
ous in a conspicuous dense furry-looking spike, many of the 
plants green, others of all shades of red and purple reminding 
one strongly of a near relative, the Celosia or cockscomb of 
gardens, the whole mass giving to shores in autumn an ap- 
pearance of a wild, barbaric mixture of splendor and somber- 
ness. Current descriptions do not give any lower limit of size. 
Britton & Brown say “Sometimes 10° high,” and Robinson & 
Fernald make no mention of size. All the plants found on the 
stretch of shore were very small, some of them minute. It 
Was a common plant and seven exceedingly small examples 
were collected, one 14.5 mm. long with a slender stem, 3 leaves 
and 4 flowers, a third specimen 31.8 mm. high, the others were 
about the same size. The year 1915, being a year of high 
water and rather few fluctuations, was not favorable for the 
development of the dwarf shore flora; however, at the edges 
of a slough known locally as Sunfish Lake, some very minute 
examples of this plant represented by little more than a little 
speck of purple, were seen. They hardly projected above the 
soil. 
