1908] HARVEY—PRAIRIE-GRASS FORMATION 291 
The prairie mugwort, Artemisia gnaphaloides, is gregarious upon 
upper slopes. Here it forms dense patches, and these, on account 
of the white tomentosity of its stems and leaves, which are frequently 
so high, are conspicuous in the dominant tone of yellow. It 
bears to the autumnal quite the relation that the. Antennarias hold to 
the prevernal and vernal tone. Perennial from a tuber-like root, it 
is also xerophytic in tendency. In its pappate achenes and root- 
Propagation are found the causes of its gregarious habit. 
The closing days of August are marked by the estivation of the 
two false bonesets, Kuhnia eupatorioides and K. glutinosa. ‘They 
both occur but rarely and then mainly upon upper slopes and crests. 
They form little clumps (several shoots from the same perennial 
Toot) and are tall (so to 75°™) and much branched, but on account 
of their small few-flowered heads of creamy-white color and their only 
occasional frequence, they never attain any prominence. However, 
they become much more noticeable when the rich white pappus 
Spreads in maturatian, during the second week of September. K. 
eupatorioides is more mesophytic and so occurs more frequently over 
the formation. XK. glutinosa, however, is pronouncedly xerophytic, 
and is restricted in its distribution to the open association along crests 
and higher slopes. The abundant barbulate pappus assures prolific 
invasion, though establishment seems to be very limited, doubtless 
rie to the apparently low degree of adaptability possessed by these 
orms, 
The Kuhnias are accompanied by Nabalus asper, which is 
restricted to lower slopes, is of rare occurrence and thus always a 
nunor element. ‘Though it is of the upper layer and bears numerous 
heads of pale-yellow flowers, it blends into inconspicuousness in the 
seneral tone, Itisa perennial from a tuberous root. A well-devel- 
Ped parachute insures wide dissemination, but high ecological de- 
mands preclude more than a rare establishment upon the prairie. 
boii mi early days of September are well marked by the blooming of 
orms which occasionally attain more or less restricted promi- 
_ Mnee: Aster sericeus , A. multiflorus, A. oblongifolius, and Kuhnistera 
— *y are all of evident xerophytic tendencies and — 
th Y upon the upper slopes and crests. Appearing at a time when 
fre Is an pparent decline in the dominance of the earlier tone, and 
