The Shrubs of Wyoming. 37 



aster, daisy, yarrow and artichoke. Plants classed in this fam- 

 ily abound in this state. 



A number of native shrubs and underbushes of the state, 

 such as the sage-brushes and rabbit-bushes, belong to the thistle 

 family. These shrubs have very small flowers little resembling 

 those of the thistle or the sunflower. 



TETRADYMIA. 



(Tetradymia). 

 The tetradymias are low grayish shrubs with yellow flowers 

 clustered at the ends of the branches. They grow naturally 

 on open plains and especially in desert regions. The seeds, 

 which are borne several together in each flower head, are sur- 

 mounted by numerous long white bristles. 



Gray Tetradymia (Tetradymia canescens DC.) 



The common species throughout the state. The whole plant 

 is gray in color. The leaves are narrow and less than an inch 

 long and the yellow flower heads are very numerous at the ends 

 of the branches. 



Nuttall's Tetradymia (Tetradymia Nuttalln T. & G.) 



A low rigid shrub with spiny branches, the short, blunt- 

 pointed leaves arising in tufts. The slender spines are a half to 

 an inch in length, and its flower heads are closely crowded to- 

 gether at the ends of the branches. This shrub occurs in the 

 arid region of southwestern Wyoming. 



Spiny Tetradymia (Tetradymia spinosa H. & A.) 



A scraggy shrub with woolly branches and very small tufted 

 green leaves. Its spines are only about one-third of an inch in 

 length and the flowers (heads), which are white- woolly on the 

 exterior, are borne singly on stoutish stalks along the branches. 

 Not uncommon in the Red Desert. This white-stemmed shrub 

 is rather pretty and of striking appearance. 



