4- BUUL/ETIN 1112, U. S. DEPARTMENT OF AGBICULTUEE. 



woods, wMle tlie genus Razoumofskya is found exolusiTely on 

 conifers. Several species of the latter genus are rather conimon in 

 the western United States and in some localities have become very 

 serious parasites. Razoumofskya cryptopoda, the western yellow 

 pine mistletoe, is one of the most widely distributed of all the species, 

 usually being found wherever the western vellow pine grows. 

 (PL I, Fig. 1.) 



Razoumofslcya cryptopoda flowers in Arizona and New Mexico 

 during April and May, and the fruit matures in August and Septem- 

 ber of the next year. When the seeds begin to ripen, the berries 

 gradually turn downward on their pedicels imtil the base of each 

 berry when fully mature points'upward. The gelatinous seeds when 

 ripe are suddenly and forcibly ejected upward to a distance of several 

 yards by the giving way of a ring of tissue situated near the base of 

 the berry. This method of seed dissemination is common to all species 

 of Razoumofskya. Experiments and extended observations indicate 

 that the aerial portions of both staminate and pistillate plants die 

 and fall from the trees after one season of flowering and fruiting. 

 (PL I, Fig. '2.) 



EFFECT OF MISTLETOE ON GROWTH OF HOST. 



The study of the effect of roistletoe on its host was accomplished 

 (1) by periodic measurements and observations of standing trees, 

 both infected and healthy; and (2) by detailed growth studies and 

 observations of infected and healthy felled trees. 



EFFECT ON BOLE OF TREE. 



Ninety-one healthy and mistletoe-infected trees between 10 and 

 30 inches in diameter breast high on three different areas within a 

 radius of 5 miles of the Fort Valley Experiment Station were tagged, 

 numbered, measured, and mapped in 1910 with the object of deter- 

 mining the effect of mistletoe on the diameter and height-growth of 

 the host, the diameter growth of limbs, and the growth of the mer- 

 chantable contents of the bole. The diameters were measured with 

 a diameter tape at 1, 4.5, 17, and 33 feet above the ground. The 

 total heights were measured with a Forest Service standard hypso- 

 meter. The diameters of 20 healthy and 34 mistletoe-infected 

 limbs falling in different infection classes were measured on 18 

 standing trees with a view of determining the effect of mistletoe 

 on .the growth of limbs. The points of measurement at 6 inches 

 from the bole of the tree and every 6 inches beyond this point were 

 marked by driving a 6-penny copper nail into the wood. All of the 

 trees were remeasured in 1915 and were reclassified into four degrees 

 of mistletoe infection, according to the prevalence of mistletoe on 

 the tree, as follows: O, healthy trees without mistletoe; X, light 



