244 The Plant World. 



on the one-seeded juniper, while in the Santa CataHnas it occurs 

 on the alligator juniper. In New Mexico it is very abundant, 

 almost destructive in places, on the former host, and also present 

 on the latter, both growing in the foothills near Fort Bayard. 



As already indicated, the true mistletoe (P. flavescens and 

 varieties) is within the zone of its hosts of wide distribution, in- 

 habitating the Elevated Central Tract, and extending eastward 

 at least to Fort Bayard and the Rio Grande. In the Dragoon 

 mountains it was first seen upon Celtis reticulata, adding another 

 host to those harboring it in the Chiricahuas. This host has been 

 noted for two localities in the San Pedro Valley, McCleary's 

 ranch in the Santa Ritas, and Rincon Creek. On the walnut 

 (Juglans major) the smooth form of the species occurs, aside 

 from the Chiricahuas, in the Dragoons, Mustangs, Santa Ritas, 

 and many other localities. Near Fort Bayard, New Mexico, a 

 smooth form was found present upon deciduous white oak, usually 

 passing as Quercus Gambelii. In the long and tortuous Cafion 

 de los Alisos it is found on ash, walnut, and black willow (Salix 

 nigra), but none was found upon the large and numerous syca- 

 mores after which this well watered canyon is named. In fact 

 the only known occurrence upon this host is on a single tree at 

 "Wilgus Ranch in the Chiricahua Mountains. On the desert 

 willow it has never been found. 



On the Cottonwood of the Sonoran Zone, usually designated 

 as Populus Fremontii, marking the best watered spots by small 

 groves and isolated trees, it has been seen on the Rio Grande, 

 the Santa Cruz, and many times between. Perhaps more often 

 than on any other tree, it is seen on the much more numerous ash 

 of the lower altitudes (largely Fraxinus velutina). Numbers of 

 these trees are apparently being killed by this parasite on 

 Cottonwood and Bonita creeks in the Chiricahuas and many 

 other places. Over the border in Sonora, on the headwaters of 

 the Rio Altar.it was discovered upon a very small and peculiar 

 ash {F. cuspidata?) and upon the soap berry {Sapindus margin- 

 atus). The latter host was seen supporting large quantities of 

 the parasite on Riacon Creek, being greatly preferred to the more 

 numerous hackberry. It is less common on the willow, for aside 

 from one or two stations in the Chiricahuas and one on the 

 boundary already noted, it was seen in the Dragoons only, on 

 Salix taxi folia. 



