1908] HARVEY—PRAIRIE-GRASS FORMATION 107 
immobility and high ecological demands result in its gregarious 
habit. The berries are persistent and birds may help somewhat in 
dispersal, 
The last of this group to bloom is Verbena stricta. About June 
25 the purplish-blue flowers make their appearance at the base of the 
long (1 5-30°™) indeterminate terminal spikes in a narrow band, which 
moves upward day by day at the rate of about 1 to 2°™. The maxi- 
mum flowering, however, seems to be reached about July Io to 20. 
és =. 3-—Late estival aspect; Verbena stricta determining the tone of a lower slope; 
© white patches are the ruderal Hordeum jubatum. 
Like Ratibida and for the same reason, it flowers abundantly through 
July brig August and into September. It has a copious and general 
distribution and not infrequently assumes a dominating influence 
etal (fig. 3) and upper slopes as well as crests. It is a per- 
it ‘tom a heavy root and several stalks from the same root give 
ci infrequently a “bunch” appearance. 
jo the last days of June and the first days of July, several 
ag to complete the estival floral aspect. In order of 
uphor = they are Acerates viridiflora linearis, Potentilla hippiana, 
¢ marginata, and Amorpha canescens. All assume local 
