286 



BOTANICAL GAZETTE 



[OCTOBER 



might be inferred, passes as the open formation gradually becomes 

 closed, never being present in a compact sod at the base of the slope. 

 Appearing with S. missouriensis comes H. scaherrimus. It occurs 

 both more frequently and abundantly than the former and is dis- 

 tinctly less xerophytic, reaching its greatest abundance upon middle 

 and upper slopes. Its rigid, rough, and Httle-branched shoots, 

 rising some i.^^ and terminated by a spreading corymb bearing 



Fig. 2. — Late serotinal aspect: Solidago rigida and Helianthus scaherrimus on 

 upper slope. 



few conspicuous heads (3 to 5'='" wide) with numerous yellow rays, 

 make it a conspicuous element of the early autumnal aspect, but it 

 soon blends in the sea of yellow of Solidago rigida, which shortly 

 comes on, completely dominating the floral tone. Helianthus 

 {fig. 2) rarely holds its own along the tension Hne where the Poa sod 

 is encroaching, but with other open association forms yields to its 

 advancement, though it occurs inclusively in the less compact sods 

 higher up the slopes, in which places it frequently assumes a copio- 

 gregarious habit. The stiff sunflower is perennial by a thick root- 



