14 



BULLETIN 360, U. S. DEPARTMENT OF AGRICULTURE. 



(fig. 12). but the stimulus to abnormal branching may continue. 

 Brooms are formed on all hosts attacked by this genus of mistletoe. 



Those of the yellow 



f 



pine, owing to their 

 loosely branched con- 

 dition (fig. 12), are 

 sometimes not as con- 

 spicuous as those pro- 

 duced on Douglas fir 

 (figs. 6, 7, and 13), 

 larch (fig. 14), hem- 

 lock (fig. 9), or lodge- 

 pole pine. 



In all the regions 

 where the yellow-pine 

 mistletoe has been ob- 

 served in the States of 

 Washington, Oregon, 

 Idaho, Montana, and 

 South Dakota, broom- 

 ing is a common result 

 of the growth of the 

 parasite on this tree. 

 Correspondents in "Wy- 

 oming, Utah, and Colorado report that old infected trees are seldom 

 without them. MacDougal (8) 1 refers to the excessive brooming of 

 yellow pine by mis- 

 tletoe in the South- 

 west. Meinecke (10) 

 refers to the very 

 conspicuous brooms 

 on Jeffrey pine, 

 sugar pine, yellow 

 pine, lodgepole pine, 

 and Douglas fir. 



The old brooms of 

 the Douglas fir, be- 

 cause of the long, 

 trailing, willowlike 

 branches of the 

 lower portion of the 

 broom, are more con- 

 spicuous than those of other conifers (fig. 13). They sometimes 

 attain an immense size, often including the entire crown (fig. 6). In 



FIG. 10. Young, first infections of RazoumofsJcya cam- 

 pylopoda on western yellow pine (Finns ponderosa). 



FIG. 11. A larch branch, showing the result of a first infec- 

 tion at its base by Razoumofskya laricis. Ihis is the be- 

 ginning of a burl at this point, which will spread to the 

 main trunk. 



1 Reference is made by number to " Literature cited," p. 39. 



