Prairie- and Sand Hill District. 537 
Lamberti, Psoralea argophylla and in many places Tradescantia virginica, all 
with blue 'flowers which display their colors to perfection against the color of 
the glistening white awns of Stipa. Tihelesperma trifidum with yellow flowers 
also are found and as of secondary importance Psoralea digitata, P. tenuiflora, 
P. esculenta also with blue flowers. Later in the summer when Sta becomes 
dry, Aster canescens, A. commutatus, Liatris punctata, Oxybaphus (Allionia) 
linearis and O. hursuta appear. 
' Bouteloua (Grama Grass) Formation. Elsewhere in Kansas on the high 
prairies are Boutıloua curtipendula (= B. racemosa), B. oligostachya, B. hirsuta, 
Lepachys tagetes, Gaillardia pulchella, Engelmannia pinnatifida, Erysimum 
asperum, Astragalus lotiflorus and mollissimus, Ipomoea leptophylla, Oenothera 
Hartwegi and the prevailing sunflower Zelianthus petiolaris. 
The same formation occupies practically the whole mesa region and the 
low land surrounding it at the eastern base of Pikes Peak in Colorado. 
It extends many miles north and south and is also typic of the high plains 
eastward. Bouteloua oligostachya is the dominant species of the formation. 
The hills and ridges are occupied by Doufteloua hirsuta, alternating with Andro- 
pogon scoparius (see Fig. 27 pag. 523) and Koeleria cristata which often become 
‚ dominant, while the grama grass occupies the sides of slopes and level 
expanses. Alternating with this are Andropogon furcatus and Calamviılfa 
longifolia. It is here that the most important associations of the formation 
are found, many of which extend for many miles without interruption. Grindelia 
squarrosa forms such an association, while Sckaedonnardus paniculatus (= S. 
texanus) and Thelesperma intermedia unite to form one. The Guterresia saro- 
Hırae association occurs more often near the mountains and Artemisia cana- 
densis is also important in similar localities. Opuntia polyacantha (= O. missou- 
riensis) and OÖ. arborescens (see Fig. 28) occur but sparingly. Other associations 
occur in which such species as Carexr stenophylla, Selaginella densa. Yucca 
angustifolia (= Y. glauca) (see Fig. 28), Plantago Purshü, Lupinus abgenteus 
are leeres 
The principal species of the Mn aspect, according to SHANTZ?) are Leucocrinum 
mo es, Festen sericea (= T. exscapa), Anemone patens (= Pulsatilla hirsutissima), while 
the secondary species are SIOBRELDB Sein (= C. acaulis), Cymopterus (Phellopterus) mont- 
anus. The greatest imnber of spring flowers are produced on the north slopes, because here 
the moisture vn of the soil is greater, and this aspect is characteristic of the mesa before 
the spring r appe The vernal aspect is ushered in with the spring rains and usually 
extends Es ne ui first of May to the middle of July. : The principal species are Senecio 
oblanceolatus, Yucca angustifolia oe . glauca), (see = I Sur yuccogena, Pleospora 
phragmospora, Astragalus Drummondii, Pentstemon coeruleus (= P. angustifolius), P. secundifloras, 
Opuntia missouriensis (= 0. abnieka). Astragalus Tee Euphorbia robusta, Uromyces 
scutellatus, Echinocereus viridiflorus, Arenaria Fendleri, Sophora sericea, nern leptophylia. The 
aestival aspect is marked by the increase in temperature and decrease in rainfall. Then, 
according to my observations the mesa is dry = the surface soil looks parched. The facies is 
due, to Bouteloua oligostachys, B. hirsuta, Andropogon scoparius, A, furcatus, Muhlenbergi 
erseie The principal species are Artemisia frigida, Gutierrezia euthamiae (G. sarothrae), Aristida 
1) Botanical Gazette XLII: 16—47, 179—207. 
