22 THE MISTLETOE PEST IN THE SOUTHWEST. 



and southwestward the mesquite is the chief mistletoe host. At 

 Bryan, which lies farther within the humid belt, the water oak is the 

 most infected species. At Marble Falls, about equally distant but 

 westward from Austin, the live oak and mesquite are reported as the 

 main hosts. So in the osage orange belt of northeastern Texas — 

 notably from Greenville to Paris — that species (Toxylon pomijerum) 

 is more infected than others. In the vicinity of Calvert, Tex., the 

 blackjack oak (Quercus marilandica) is abundantly infected, but other 

 species not notably so. In reality, the species most infected in all 

 these instances are either the most abundant or else the most promi- 

 nent in certain situations; for example, along water courses or about 

 farmyards and in towns. Even so, it is not clear why, for instance, 

 the blackjack oak, which is the prevailing host in certain districts, 

 should be comparatively immune in another district where mistletoe 

 is even more common. Extending the range of observation, it is 

 found that the dominant host for Phoradendron Jlavescens and its 

 different forms varies with the geographical location, as follows: In 

 the South, the water oak and other red or black oaks of wet soils, 

 gums, elms, and sycamores; in the Santa Clara Valley, California, 

 especially on deciduous oaks (the prevailing form here being Phora- 

 dendron jlavescens villosum); in southern California Phoradendron 

 jlavescens macrophyllum on the poplar, willow, ash, and others; at 

 Tucson, Ariz., Phoradendron jlavescens macrophyllum on the poplar 

 (cottonwood) , ash, and black locust, said Phoradendron jlavescens vil- 

 losum on oaks and the hackberry. 



LIST OF HOSTS OF THE MISTLETOE IN TEXAS. 



Pecan (Hicoria pecan (Marsh.) Britton). 

 Hickory (Hicoria species). (At Columbus, Tex.) 

 Post oak (Quercus minor (Marsh.) Sargent). 

 Bur oak (Quercus macrocarpa Michx.). 

 Texan oak (Quercus texana Buckl.). 

 Water oak (Quercus nigra L.). 

 Willow oak (Quercus phellos L.). 

 Blackjack (Quercus marilandica Muench.). 



Live oak (Quercus virgihiana Mill.); (Marble Falls and Comanche, Tex. ; not noted at 

 Austin). 



Cedar elm ( Ulmus crassifolia Nutt.). 

 White elm or American elm ( Ulmus americana L.). 

 Hackberry or Sugarberry (Celtis mississippiensis Bosc, and varieties). 

 Osage orange (Toxylon pomiferum Raf.). 

 Paper mulberry (Papyrus papyri/era (L.) Kuntze). 

 Sassafras (Sassafras sassafras (L.) Karsten). 

 Sweet gum (Liquidambar styraciflua L.). 

 Apple (cultivated varieties). 

 Pear (cultivated varieties). 

 Cherry (Prunus species, wild). 

 166 



