FLOWERING PLANTS AND FERNS OF ARIZONA 233 



Parasitic on junipers. The species is represented in Arizona by 

 var. capitellatum (Ton*.) Kearney and Peebles (P. capitellatum Torr.), 

 distinguished from the typical form chiefly by the decidedly pubescent 

 herbage. 



4. Phoradendron densum Torr. ex Trel., Gen. Phoradendr. 27. 1916. 

 Flagstaff, Coconino County (Hedgcock 4915, part, cit. Trelease 



ibid.), Reno Pass, Mazatzal Mountains, Gila County (Peebles 11557), 

 3,500 to 7,000 feet. Oregon to Sonora. 



Parasitic in Arizona on Cupressus glabra, elsewhere also on Juniperus. 



5. Phoradendron pauciflorum Torr., U. S. Rpt. Expl. Miss. Pacific 4 4 : 



134. 1857. 



Sedona (Coconino County), Mazatzal Mountains and Natural 

 Bridge (Gila County), Santa Catalina Mountains (Pima County), 

 4,200 to 7,700 feet. Arizona, California, and Baja California. 



Parasitic on Cupressus in Coconino and Gila Counties, on Abies in 

 the Santa Catalina Mountains. 



6. Phoradendron macrophyllum (Engelm.) Cockerell, Amer. Nat. 34: 



293. 1900. 



Phoradendron jlavescens (Pursh) Nutt. var. macrophyllum 

 Engelm. in Wheeler, U. S. Survey West 100th Mer. Rpt. 6: 

 252. 1878. 



Yavapai County to Cochise, Santa Cruz, Pima, and (probably) 

 Yuma Counties, 5,500 feet or lower, very common. Western Texas to 

 California and Sonora. 



The most conspicuous and largest leaved of the Arizona mistletoes, 

 growing in great masses, commonly on cottonwood (Populus fremontii) 

 but also on sycamore, ash, hackberry, walnut, and willow. This 

 species greatly resembles the common mistletoe of the eastern United 

 States, P. jiavescens Nutt. Trelease distinguishes two varieties based 

 on collections in southern Arizona: var. circulare Trelease (type 

 Griffiths and Thornber 191 from the Santa Rita Mountains) with 

 nearly orbicular leaf blades, and var. jonesii Trelease (type Jones 

 4281 from Bowie) with oblanceolate or obovate leaf blades; but this 

 range of variation is sometimes found on the same individual. P. 

 longispicum Trelease appears to be merely a more pubescent form of 

 P. macrophyllum. P. coloradense Trelease, described as having oblan- 

 ceolate or obovate leaf blades and reported as growing on Prosopi* in 

 the lower Colorado River region, also seems scarcely separable from 

 P. macrophyllum. 



7. Phoradendron coryae Trel., Gen. Phoradendr. 43. 1916. 

 Southern Coconino Count} 7 to Cochise, Santa Cruz, and Pima 



Counties, 3,500 to 8,500 feet. Western Texas to Arizona and Sonora. 

 A very common species in Arizona, parasitic on several evergreen 

 species of oak, rarely on barberry (Berberis haematocarpa). 



2. ARCEUTHOBIUM.3 3 Small-mistletoe 



Plants without chlorophyll, parasitic only on conifers; leaves reduced 

 to connate scales; flowers solitary or several in the axils of the scales: 

 perianth with a basal disk. 



33 Reference: Gill, L. S. arceuthobium in the united states. Conn. Acad. Arts and Sri. Trans. 

 32: 111-245. 1935. 



