MISTLETOE INJURY TO CONIFERS. 19 
ceases to grow in length and instead forms: abnormally abundant 
lateral branches. The terminal buds of these are likewise overtaken 
by the parasite, resulting in additional lateral branches, and so on, 
until a type of dichotomous branching results. This is more notice- 
able in the compact type of broom than in the long, trailing type, but 
is quite common in both, especially on exposed and wind-swept areas. 
A very interesting hypertrophy of the foliage spurs is often 
shown by the brooms 
of the larch. The 
spurs are frequently 
abnormally large 
and may be four or 
five times as long as 
those of normal 
branches . (fig. 16). 
On such spurs the 
needles are usually 
shorter and spar- 
ingly clustered. 
Eventually the para- 
site enters the spur 
and kills it. Not in- 
frequently a mistle- 
toe plant is found 
crowing out at the 
apex of the spur or 
from its side, caus- 
ing great distortion 
and the total disap- 
pearance of the nee- 
dles, and eventually 
the death of the spur. 
The reduction of Fic. 16.—Abnormal foliar spurs of the western larch caused 
foliage by the thin- by. Razoumofskya laricis. Note their size as compared 
3 5 with normal spurs. 4 
ning and shortening : 
of the needles of the trees as a whole, and of the brooms sooner or 
later, is characteristic of mistletoe infection on all hosts. 
The food material, which undoubtedly is accumulated in the 
brooms, seems to be entirely appropriated at these points and does 
not serve the host as a whole. The support of the excessive number 
of branches is necessary, but the parasite itself undoubtedly appro- 
priates a large share at the expense of the healthy branches. The 
yellow-pine mistletoe has been observed to become more luxuriant 
and to develop abnormally long stems on swellings which had been 
lacerated or gnawed by rodents. Evidently the accumulation of 
