1908] HARVEY—PRAIRIE-GRASS FORMATION 287 
stock. A very limited pappus of two to four'scalelike awns provides 
only a restricted distribution, easily accounting for its gregarious 
tendency. 
About a week or ten days later S. rigida begins its blooming, but 
only reaches its maximum about the last of the month, at this time 
solely characterizing the floral tone and maintaining a sea of yellow 
for some three weeks, when the tone begins to pale as fruiting advances 
and completely gives way during the third week of September, the 
bright-yellow floral tone yielding to the dull-green foliage. The 
stiff goldenrod occurs ubiquitously, but reaches its greatest abundance 
upon middle slopes, where it is frequently copious. The single stout 
stem (frequently several), from the perennial rootstock, rises some- 
what over a meter, terminating in a flat dense cyme bearing numerous 
yellow-rayed flowers, frequently 20 to 25°™ across, which with its 
abundance and frequency makes 5S. rigida the most striking and 
dominating in its floral tone of any single species of the formation. 
Following the latter species by only a few days S. nemoralis comes 
into bloom. Overtopped by and much less abundant than the former, 
It Never is conspicuous, though frequently it adds to the dominant 
yellow tone of the aspect. It reaches its greatest abundance on 
slopes, occasionally entering the open association of the crests, but is 
rarely included in the compact sod of lower slopes. 
The three goldenrods just noted are alike perennial from a thick- 
fned rootstock, with a tendency toward the formation of perennial 
basal Tosettes, and are widely wind-disseminated through the effi- 
ciency of the well-developed parachute. 
Almost coincident with the blooming of these four forms is that 
of the bunch-grasses, Andropogon furcatus and A. scoparius. Though 
these two grasses during the last two aspects have been vegetatively 
©onspicuous upon the higher crests and most xerophytic slopes, where 
they Contribute the characteristic dull tone to the bunch-grass asso- 
eo, they flower only during the early part of August, thereby 
adding but little to their already established prominence. They are 
“companied by Sporobolus brevifolius, which occurs less abundantly, 
Dut like the beard-grasses assumes the bunch habit upon higher 
a and ridges. In these situations the Andropogons oe 
acial Tank, A. Surcatus ( fig. 3) being the taller and on account of its 
