1918] WEIR—RAZOUMOFSKYA 25 
americana, but that occasionally other hard pines are attacked. 
The writer has previously reported the occurrence of this mistletoe 
on Pinus attenuata, P. Jeffreyi, 
and P. ponderosa, and it has 
long been known to be 
common on Pinus Banksiana 
in Canada. The fact that this 
mistletoe will infect Pinus 
montana, the common moun- 
tain pine of Europe, further 
supports the writer’s conten- 
tion that it may be expected 
to occur occasionally on any 
of the hard or yellow pines, 
and also is a warning that the 
parasite would probably find 
a favorable home in Europe. 
ae plant apparently attacks Fic. 16.—R. americana on Pinus bade. 
the yellow pines other than __,,.. oO Ger plants. 
Pinus contorta with difficulty. 
Such infections are by no means common, and frequently result in 
some morphological changes in the plant. These changes, how- 
ever, may not be any more 
marked than those the plant 
may exhibit when developing 
under various light intensities 
or varying conditions of 
nourishment on its regular 
host. If R. americana ex- 
hibits a certain antipathy to 
other yellow pines, it appar- 
ently has a much greater 
aversion to white pine. That 
Fic —R. americana on Pinus contorta: the species will infect white 
viseitate' binsita: : . a 
pines but with difficulty, and 
will never be of consequence in this respect, is shown by the 
discovery of two infections on Pinus albicaulis near Darby, 
isi 
Ayo a ay spay UW 
metric !isystem 
