MISCELLANEOUS PARASITIC AND SAPROPHYTIC ORGANISMS. 17 



is known as a "witches' broom." (See fig. 2.) During the course 

 of the development of these witches' brooms the sap becomes diverted 

 more and more completely from the outer end of the affected branch 

 to the broom, and finally that part of the branch located beyond the 

 base of the parasite dies. These witches' brooms vary much in size, 

 being from only a few inches in diameter to as much as several feet in 

 diameter and in height. The distribution of the seeds is such that a 

 tree once infected is almost sure to become more affected as time 

 goes on, so that in extreme cases there seems to be little doubt that 

 large trees may be 

 entirely killed by the 

 effects of this plant. 

 The senior writer (7 7 ) 

 has referred to the 

 apparent destructive 

 action of this plant. 

 It is evident that 

 the most practical 

 method of eradicat- 

 ing this parasite is by 

 cutting all of the af- 

 fectedtreesandburn- 

 ingtheinfectedparts. 

 It is believed that 

 a number of epi- 

 phytic plants some- 

 times bring about a 

 diseased condition of 

 deciduous trees by 

 smothering the 

 younger leaves and 

 branches. (See fig. 

 3.) The southern 

 moss ( TiUandsia 

 usneoides L.) is be- 

 lieved by many to cause the death of leaves and branches of the 

 live oak (Quercus virginiana Mill.), red gum (Liquidambar sti/raci- 

 fiua L.), and other deciduous trees. The dense masses of this 

 plant frequently cover the growing parts of the tree and deprive 

 them of air and light. Another species, TiUandsia recurvata L., 

 has recently been reported as killing the live oak (Quercus virginiana 

 Mill.) and pecan (Hicoria pecan (Marsh.) Britton) in southern 

 Texas. In the Northern States mosses and lichens frequently 

 grow in such profusion that injurious results follow. This is par- 



149 



FIG. 3. Spanish moss on a large oak tree. Note that the branches 

 bearing the moss are dead . 



