TEE GREAT AMERICAN DESERT 



217 



Fig. 3. The Dagger Weed in Feuit. 



the development of these netted 



trails. They are not necessarily 



always associated with the dagger 



weed, since they also occur on 



slopes with bunch-grasses only. 

 Like the little blue stem, the 



dagger weed has little value in the 



region aside from its interesting 



and important role in the life his- 

 tory of the ridges and slopes. Some 



economic value is attached to it in 



that it is eaten by cattle to a slight 



degree. Especially when the plant 



is in bloom, if the range is rather 



short, stock frequently strip every 



juicy flower from the large spike 



or panicle, sometimes even eating 



the axis well down among the 



needle-tipped leaves. I have seen 



them attack the young capsules 



when the range is especially short, so that in a closely grazed pasture 



one seldom finds a single fruit of the species. 



Besides the bunch-grasses and the dagger weed there are many other 



species that occur in greater or lesser frequency in the bunch-grass as- 

 sociation. The hairlike eragrostis 

 {Eragrostis trichodes) is an im- 

 portant secondary grass of the up- 

 lands that frequently shows the 

 bunch-grass haljit. So also Indian 

 millet (Oryzopsis cuspidata) , and 

 the black grama grass (Bouteloua 

 hirsuta) are quite commonly seen 

 in the intervals between the bunch- 

 grasses. In fact there are more 

 than one hundred species of grasses 

 alone in the Sand Hills, many of 

 which are confined to the uplands. 

 Besides the species already men- 

 tioned the following are other 

 common associates of the bunch- 

 grasses : Annual eriogonum (Eri- 

 og 01121171 annuum) which, with its 

 slender, gray flowering stems 



and conspicuous flat-topped clus- 

 FiG. 4. The Dagger Weed may Adjust ^ . 



ITSELF TO A CHANGING SOIL LEVEL. tcrs of flowcrs, occurs as widely 



