2l8 



THE POPULAR SCIENCE MONTHLY 



Fig. 5. A Blow-out from the West. Bunch-grasses on the outside, Rcdfleldia on 



the inside. 



scattered individuals here and there, or may occasionally form rather 

 dense communities; spiderwort (Tradescantia virginica), tufted 

 hymenopappus (Hymenopappus filifolivs), purple blazing star {Laci- 

 naria sqnarrosa), lance-leaved psoralea {Psoralea lanceolata), west- 

 ern thistl? {Cardiius plattensis), rough sunflower (Helianthus 

 scaberrimvs), prickly poppy {Argemone intermedia), long-leaved 

 milk vetch (Phaca longifolia) , green milkweed [A cerates viridiflora), 

 switch grass (Panicum virgatum), prairie pink (Lygodesmia juncea), 

 Geyer's spunge (Euphorbia geyeri), yellow evening primrose {CEno- 

 thera romhipetala) , sweet pea (Lathyrus ornatus), and hairy golden 

 aster (Chrysopsis villosa). All of these plants occur as scattered indi- 

 viduals except the milk vetch and prairie pink, which are often gre- 

 garious. They all show striking anatomical characters that doubtless 

 aid in their survival in such dry soils, exposed to such trying climatic 

 conditions. 



In addition to the grasses and the common herbaceous associates the 

 vegetation of the upland is rich in species of low shrubs. In many re- 

 stricted localities these under-shrubs compose the bulk of the vegetation 

 and really rival the bunch-grasses in dominance. Among these low, 

 much branched, woody plants, New Jersey tea (Ceanothus ovatus), 

 Bessey's sand cherry (Pruniis Besseyi), poison ivy (Rhus radi- 

 cans), and the prairie clovers (Kuhnistera purpurea^ K. villosa, 

 and K. alba) are the commonest and most widely distributed. 

 All of these plants are dwarfed, much branched shrubs often grow- 

 ing in communities. 'New Jersey tea is found most frequently near 

 the tops of the hills on north facing slopes, where the dense, light 



