242 The Plant World. 



is harder and more brittle. Its smooth forms, having larger leaves 

 are common and sometimes of overpowering abundance, on 

 such v/ater-loving trees as ash, walnut, cotton wood, and soap- 

 berry {{Sabindus marginatus). But the sycamore (Platanus 

 Wrightii) and the desert willow {Chilopsis linearis), of the same 

 habitat, are practically immune. The desert willow, in one 

 instance on Bonita Creek, Cochise County, Arizona was found to 

 divide the ground with ash. This was being exterminated by 

 very numerous bunches of mistletoe, but not one could be detect- 

 ed upon the desert willow. No experiments are necessary to prove 

 its immunity under the conditions there given. It is valued 

 by stockmen as an excellent and durable wood for fence posts, 

 also in this respect showing affinity with its bignoniaceous 

 relative, the famous catalpa. No great damage by mistletoe 

 need therefore be feared in reservations or plantations of desert 

 willow. 



It is the pleasing green, luxuriant development, and abund- 

 ance of white berries of the s nooth-leaved forms of this variable 

 species, growing near ranches, settlements and in riparian situ- 

 ations generally, that make the mistletoe much sought for 

 Christmas and other decoration. 



Finally, the false mistletoe (P. calif or nicum) is entirely 

 Lower Sonoran in choice of hosts and hence in distribution. 

 Its leafless character fits well into the drouth and heat of the 

 desert, nevertheless it manifests a preference for the larger, 

 comparatively well-watered individuals of mesquite and Acacia 

 Greggii. Groups of trees near water or human habitations are 

 occasionally found heavily infested with this thrifty parasite, 

 bearing quantities of red berries. It is hoped to touch upon the 

 causes governing its distribution at another time. 



To substantiate what has been said mainly in outline, and 

 for more exact reference, the records follow, for the sake of 

 brevity only partially detailed. At present no attempt is made 

 to give the references in literature. In 1906, six species of mistle- 

 toe were recorded as occurring upon 20 host species in various 

 parts of the Chiricahua Mountains, nearly all occurrences upon the 

 different hosts having been collected and distributed. These 

 are as follows: 



