1908] HARVEY—PRAIRIE-GRASS FORMATION 103 
of the most conspicuous elements of the early estival aspect. Its 
prominence, however, is of passing duration, as the petals fall after 
several days and it passes into obscurity. Mobility is limited, result- 
ing largely in the gregarious distribution. With Rosa, blooms Del- 
phinium carolinianum. It is a perennial with a thick heavy root- 
stock, and occurs sparsely as a xerophyte inthe open association upon 
upper slopes and crests. It is closely associated ecologically with 
the bunch-grasses and invariably seems to follow them. Its single 
erect stalk, some 6 to 84" high, bears a large terminal raceme of con- 
spicuous white flowers. Rising thus so conspicuously, these plants 
seem like sentinels of the prairie and a few individuals are noticeable 
at some distance. Many seeds are produced, but mobility is slight. 
The anthesis of Erigeron ramosus usually precedes that of Del- 
phinium but follows that of Rosa, only a day or two separating 
them. Erigeron is a perennial or annual occurring along upper 
slopes, where it assumes a copiogregarious habit of growth. It seems 
quite restricted, few scattering individuals being noted. It is some 
7 or 8™ high, with several stalks rising from a single root, which 
are terminated by spreading corymbs bearing numerous flowers with 
yellow disks and abundant white rays; thus it is very conspicuous. 
The achenes are provided with a double pappus, but mobility would 
seem limited, judging from the gregarious tendency of distribution. 
Brauneria, though occurring sparsely upon the highest slopes and 
Crests, is one of the most conspicuous early estival bloomers. It is a 
Xerophytic perennial with a large thick root. A single stalk, some 
7 or 8™ high, is terminated by a single large head of flowers frequently 
sm across. The numerous long pinkish ligulate ray-flowers surround 
a large reddish-brown hemispheric head bristling with abundant 
Toughish chaff; in all a very prominent structure. The achenes are 
‘towned with a short-toothed pappus, thus insuring mobility, though 
of @ low degree. It is to be noted that Brauneria has a blooming 
od of nearly two months, so it remains a conspicuous element 
€ven into the following aspect. : 
Scarcely have these forms flowered, when two species of secondary 
ele begin to make their contribution to the floral aspect, 
ming progressively during the earlier part of the third week of 
June, They are Anemone cylindrica and Physalis heterophylla. 
