599 



70. Popidiis trcmuloidcs Michx, 



In thickets, small patches of forest, etc. ; frequent. 



71. P. grandidcntata Alichx. 



With the last, but rather rare. 



y2. P. dcltoides Marsh. 



Along ditches and roads ; merely a few scattered trees. 



Urticaccae 

 '/2>- U I mils aincricana L. 



A few large trees here and there. (PI. XCYI, Fig. 22.) 



Polygonaceae 



74. Riiincx britannica L. 



In the reed swamp ; f recjuent. 



75. R. crispiis L. 



Occurring sparingly in the meadow (but common along the 

 roadsides). 



76. R. altissii}ius Wood 



In the swamp meadow ; occasional. 



yy. R. vcrticiUatiis L. 



Very abundant at many points in Skokie Stream ; frequent 

 in other parts of the reed swamp. 



78. Polygonum avicidare L. 



In the meadow, where principally along paths ; occasional. 



79. P. lapathifoliiiiii L. 



In the swamp meadow ; rather common. 



80. P. Miihlcnbcrgii (Meisn.) Wats. 



Abundant in the reed swamp; frequent in the swamp meadow. 



81. P. pcnnsyh'anicum L. 



In a few open, fairly dry areas of the reed swamp; not com- 

 mon. 



82. P. Hydropipcr L. 



Mostly in the Irido-acoretum of the reed swamp; common, 

 becoming very abundant at certain points. 



83. P. acre HBK. 



Occurring with P. Hydropipcr, but less abundant. 



84. P. Persicaria L. 



Scattered, in open parts of the swamp meadow ; frequent. 



