102 BOTANICAL GAZETTE [AUGUST 
respectively. Yet the average chresard for the aspect (8.8 per 
cent.) shows a steady decrease from that of the vernal (10.7 per 
cent.). 
SPECIES OF THE ESTIVAL FLORAL ASPECT 
Factes.—Koeleria cristata,t Poa pratensis.*t 
PRINCIPAL SPECIES.—Ratibida columnaris,t Amorpha canescens, Erigeron 
ramosus,{ Symphoricarpus occidentalis,t Verbena stricta,t Festuca octoflora.f 
Euphorbia marginata, Potentilla hippiana, Plantago Purshii,* Hedeoma hispida,* 
Polygala alba,* Hedeoma hispida.* 
TERTIARY SPECIES.—Stipa spartea, Aristida purpurea, Allionia linearis, 
Acerates viridiflora linearis, Osmodium molle,* Anemone cylindrica, Physalis 
heterophylla, Gaura parviflora, Gaura coccinea. 
RUDERAL sPECIES.—Hordeum jubatum, Ixophorus viridis, Panicum capil 
lare, Melilotus alba,* Lappula Lappula,* Verbena bracteosa, Allionia nyctaginea, 
Potentilla monspeliensis, Melilotus officinalis,* Lepidium virginicum.*. 
* From earlier aspect. + Forming associations. 
Koeleria cristata is a perennial bunch-grass and a very important 
sod-former, and may be considered one of the forerunners of the blue- 
grass. It occurs generally distributed higher up the slopes, where not 
infrequently it may reach facial rank. Above it seems to be encroach- 
ing upon the grama and buffalo grasses and so is quite lacking # 
the crests. Panicum Scribnerianum is likewise a perennial of the 
bunch habit and is closely associated with Koeleria in distribution, 
but never appears so abundantly as to become a facies. It is evi 
dently more of a mesophyte than the latter and follows it up the 
slopes. In the formation studied it is mostly confined to the lower 
part of the middle slopes. It blossoms slightly before Koeleria. 
Stipa spartea is likewise a bunch-grass and the most xerophyti¢ 
these three grasses. It is sparsely distributed upon the uppermost 
slopes and crests and never forms a facies. It must be rated as 
unimportant element in sod-establishment in the formation. 
Almost coincident with the sod-formers listed above, blooms the 
prairie rose, Rosa arkansana. It is the first woody perennial to bloom 
and is distributed over upper slopes and crests where in the lett 
habitat it commonly becomes copiogregarious. Its abundanc® 
large pink flowers, general anthesis, and height make it always a : : 
ae 
| 
| 
