Vegetation of the Sand-hill Region. 239 
Erysimum asperum DC. ' Orobanche ludoviciana Nutt. 
» > DC. var. Arkansa- Dalea (Parosela) aurea Nutt. 
num (=E. arkansanum Nutt.). | Physalis lanceolata Michx. 
Galium boreale L. Phlox Hoodii Richards. 
Gnaphalium palustre Nutt. Pentstemon gracilis Nutt. 
Geum strictum Ait. Pinus ponderosa Lawson var. scopu- 
Gyrostachys (Spiranthes) stricta Rydb. lorum Engelm. 
Hordeum pusillum Nutt. Plantago eriopoda Torr. 
Juncus bufonius L.._ Sophora sericea Nutt. 
Lacinaria (Liatris) spicata L. Sporobolus airoides Torr. 
Leucocrinum montanum Nutt. Stipa comata Trin. & Rupr. 
Lychnis Drummondii Wats. Thelesperma trifidum Poir. 
Mentzelia nuda Torr. & Gray. Thermopsis rhombifolia Nutt. 
2 decapetala Pursh. Townsendia grandiflora Nutt. 
Monarda citriodora Cerv. Woodsia oregana D. C. Eaton. 
Opuntia fragilis Nutt. 
If a comparison is instituted between the sand-hill formations and those of 
the prairie formations proper, it becomes evident, that the prairie element con- 
sisting of such species, as Andropogon scoparius, A. provincialis, Koeleria 
cristata, Eatonia obtusata and Panicum Scribnerianum occur in bunch grass 
formation of the sand hills, so that the bunch grass formation comprises plants 
of the prairie formation proper. These plants constitute the prairie element 
of the sand-hill flora. On the other hand, such plants as Redfieldia flexuosa, 
Muhlenbergia pungens, Eragrostis trichodes, Cristatella Famesii and Polanisia 
trachysperma are peculiar to the sand-hills and may be looked upon as the 
proper elements. It is further evident that the plants of the blowout and sand 
draw formations constitute the sand-hill flora par excellence, while those of 
the bunch grass formation show decided affınities to the prairie flora proper. 
The species of Artemisia, Sarcobatus vermiculatus, and the like, in the 
prairie province are Great basin elements. On the other hand, the under- 
shrub formation of table-lands and bad lands are not proper foot-hill formations, 
nor are they proper to the prairie provincee. Where any of the species of 
"these formations invade other regions of the prairie province, we may call 
them foot-hill elements. But in the province as a whole, these species 
are Great Basin floral element, and the formations are Great Basin elements 
in the vegetation of the foot-hill region. 
The flora of the central North American plains has thus been analyzed. 
The old vegetable covering of the plains consisting of plants developed there 
under the peculiar conditions of environment has been invaded by a number 
of distinct elements from adjacent regions, so that the prairie flora proper, 
the sand-hill flora and the foot-hill flora, is a composite one consisting of 
endemic elements associated with the derived, all of which elements have been 
discussed and set forth in a differential manner above. 
