STRUCTURE OF THE FORMATION 89 



Helianthus scaberrimus is a gregario-copious or subcopious 

 xerophyte of Great ridge. It grows mostly in patches of con- 

 siderable extent, though frequently occurring sparsely for 

 some distance, especially in low prairies. The rigid, scabrous 

 stems, often much reduced on the ridge, attain a height of ^- 

 1^ meters and terminate with a few long-pedunculate, con- 

 spicuous, yellow and purple heads, about the middle of July, 

 and continue until October 1, during a portion of which time 

 patches of these plants contrast sharply with the surrounding 

 floral covering. Helianthtis maximilmni grows at a few places 

 along the slopes of the ridge ; the individuals are usually low, 

 gregarious, and grayish-canescent. The dwarf, few-flowered 

 plants of this species growing in xerophytic conditions are 

 in striking contrast with the tall, robust, many-flowered in- 

 dividuals of more favorable circumstances. H. maximiliani 

 and H. scaberrimus are perennial by thickened rootstalks. 



Of the three xerophytic goldenrods, Solidago rigida, 8. 

 rigidiuscula, and 8. nemoralis, all frequenters of the ridge, 

 the first is the most frequent and also the most abundant, 

 occurring in eighteen out of twenty-six quadrats with an 

 average of 12-15; the second is found in nine quadrats out 

 of twenty-six with an average of five individuals; the third, 

 8. nemoralis, is found at only a few stations on the ridge 

 and northern slopes near the creek. Solidago rigida is dis- 

 tributed rather evenly throughout its range and during its 

 flowering period. The rigid, coarse stems, crowned with a 

 dense, yellow corymb, are conspicuous objects of ridges and 

 slopes. The bitter juice of the stem prevents the plant from 

 being eaten, and hence we find this species one of the com- 

 monest of the "pasture weeds." A few leaves at the base of 

 the stem usually remain green through the winter, which 

 means, perhaps, the beginning of a rosette. The most showy 

 goldenrod in the prairies is 8. rigidiuscula; its terminal ob- 

 long heads, usually 5-20 from one root, appear with the last 

 flowers of the serotinal period and continue for a month or 

 more, during which time they are the most showy of the gold- 



