534 Part IV. Chapter 3. 
(= @G. sarothrae), singly or collectively constitute the principal facies in the 
middle prairie region. The secondary species are few and unimportant. The 
undershrubs are sparsely disposed and with these a few isolated mats of Boute- 
loua and occasional stragglers of Fectis are about all that are to be found. 
However, a very pronounced formation of the sage-brush kind takes exclusive 
possession of extensive sandy areas in the table-lands of the foot-hill region. 
Artemisia filifolia (see Fig. 27 page 523) constitutes the sole facies. It grows 
in dark green bunches, 3—5 centimeters wide and very high. These bunches 
stand less than a meter apart and at the edges of the formation by several 
meters. These areas are readily discernable at a considerable distance. Arte- 
misia frigida is frequentliy a secondary species. Carex stenophylla is the 
characteristic turf-builder of this formation, while Stzpa comata, Bouteloua oligo- 
stachya, Calamagrostis (Calamovilfa) longifolia, although present, are of little 
importance. Some species have been derived from the eastern sand-hills: 
Fsoralea lanceolata, Chrysopsis villosa, Helianthus petiolaris and Lathyrus 
polymorphus (= L. decaphyliu). 
Greasewood-white-sage Formation. The loose and easily eroded soil of the 
Bad Lands due to the washing away of canyon sides and buttes together 
with the heat and slight rainfall combine to render the vegetation a meager 
one. Two undershrubs give name to the formation, viz: the greasewood Sar- 
cobatus vermiculatus and the white sage Eurotia lanata. 
Some secondary species that take part in the formations are found in the edges of the Bad 
inor (= Ptiloria tenuifolia) is a sec ndary species. In barren gulches 
t1 
Calamagrostis (Calamovilfa) longifolia is in the Bad Lands of Nebraska. In the Dakotas, bunch- 
zopsis (Eriocoma) cuspidata, Andropogon scoparius are reported as well. Cnicus 
(Carduus) undulatus, Aster multiflorus, Gutierrezia euthamiae (= G. sarothrae), Bigelovia graveolens 
(= Chrysothamnus nauseosus), Musenion tenuifolium, Mentzelia ornata (= M. decapetala), Oeno- 
thera caespitosa, Lesquerella Ludovieiana (= L, argentea) and Eriogonum Jamesii have been 
observed usually along the edges. This list shows how barren and sterile such a territory is. 
Cercocarpus Scrub Formation. This scrub formation, according to RAMALEY”) 
exists in north central Colorado where the Cercocarpus bushes grow three 
feet tall and are, as a rule, so closely associated that it is difficult to walk 
between them. Sparsely distributed over the landscape, the botanist sees trees 
of Pinus ponderosa var. scopulorum and Juniperus (Sabina) scopulorum. On 
limestone ledges the shrubs are often distantly placed. 
si 
speciosa, Leucocrinum montanum, Astragalus Drummondii, A. caespitosus, Oxytropis multiceps, 
Pentstemon secundiflorus (= unilateralis), Mertensia brachyloba. e following plants are 
occasionally found: Yucca angustifolia (= Y. glauca), Helianthus petiolaris and Arenaria Hookeri. 
I 
— 
University of Colorado Studies V: 119-131. 
