1908] HARV EY—PRAIRIE-GRASS FORMATION 
less than appeared in the vernal aspect. It 
should also be noted that six new ruderals 
areadded. Panicum capillare and Hordeum 
jubatum not infrequently attain no small 
significance. The latter frequently estab- 
lishes in waste situations exclusive associa- 
tions. Its permobile awned spikelets being 
readily carried by wind or animal, its migra- 
tion is rapid. In the autumnal aspect P. 
capillare becomes detached at the surface, 
and the large and profusely branched panicles 
go tumbling over the prairie until lodgment 
Stops the distribution. 
In addition to the floral delineation of 
the vernal. The average hourly wind velocity 
1S 0.9 less and the relative humidity 3.4 
lower, the lowest of any aspect. Coupled 
wah: these conditions is the fact that the 
relative evaporation is 1.6 higher, the greatest 
“vaporation of any aspect occurring in the 
estival, 
: The holard has a slight rise in the aspect 
ue to the heaviest mean daily rainfall of the 
season. The chresard thus rises to 11 per 
fent. on June 6 to fall to 8.9 per cent. on June ~ 
22 and 6.5 per cent. on Jul On June 22 
distinction of ic : 
Ri the base, slope, and crest registering 
holard of 15-9, 16.1, and 16.6 per cent. 
position seemed nearly elimi- 
ESTIVAL CLIMATOLOGY 
IOI 
a 
NOLLVHOdVAR a 
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ALIGUYOH ~ 
FALLV1Ga NVAST "4 
oS 
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a) 
8 sepa | OS 
ae oe 
™ 
So 
pie[o 
uRayy > 
Aysuaqut rae 
“ampPy | 
Bi *yuao sod Yo) 
S ww 
= aurysung 
ssourIpnoyo ae 
uBayy + 
5 
o 
rol | 
a 
§ 
Ei A[rep uvayy 2 
sieq | 
AqDopa “s 
“Apmopy | 99 
8 quow 3 
-saomrejoy, | 2 
4 é 
| 
nm 
3 
nas 
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3) 
: CREO | 9 
3) 
—— % 
