292 BOTANICAL GAZETTE [october 



occurring in the open association, the Asters become quite noticeable 

 though they are all of a lower layer than S. rigida. The silky Aster, 

 A. sericeus, usually of low abundance and general occurrence, fre- 

 quently becomes copious on bunch-grass knolls, there forming very 

 distinct associations. Rising some 50^™, with numerous spreading 

 branches terminating in prominent heads (2 to 3'=™ in diameter) with 

 numerous violet rays, and bearing abundant leaves which are densely 

 covered above and below with a silvery-white silky pubescence, this 

 Aster is always a conspicuous element of the middle and late autumnal 

 aspect. Its achenes are equipped with a medium pappus. It is 

 a perennial from a thickened rootstock. 



The two other Asters are similar in frequency and abundance to 

 A. sericeus, but never attain its prominence. Of these A. oblongi- 

 folius always occurs with A. sericeus in the open association. With 

 us it always remains depauperate. Seldom more than 30'='" high, 

 it is ever inconspicuous, though its bluish rays make it noticeable at 

 short range, since it is usually overshadowed by A. sericeus. It is a 

 perennial and is wind-distributed; a copious pappus serves to bring 

 about a general invasion, which, as in the other Asters, seems to be 

 coupled with a high percentage of estabhshment, especially in the 

 open xerophytic associations of the formation. The dense-flowered 

 aster, A. multiflorus, occurs perhaps more frequently but less abun- 

 dantly than the former, and is similarly a xerophyte of the open asso- 

 ciation, in which situations it never reaches other than a reduced 

 stature. However, its bushy spreading branches, thickly beset with 

 numerous small white heads, invariably make it more prominent 

 than A. oblong if oliiis, particularly when it occurs in patches. It 

 seems to work down upon the lower slopes, here attaining a greater 

 stature and abundance as well as a greater prominence in anthesis. 



All the Asters are perennial from rootstocks and form small basal 

 rosettes, and are wind-disseminated. 



The hairy prairie clover, Kuhnistera villosa, is a perennial from a 

 deep tuberous root. Densely silky pubescent, abundantly branched, 

 and terminating in cyhndrical clustered spikes (3 to 6'='" long) of 

 rose-purphsh flowers, it is in itself quite conspicuous, but its restricted 

 frequency and rare abundance make it rarely a tonal component in the 

 formation. In the bunch-grass formation it becomes, with Amorpha 



