18 BOTANICAL GAZETTE [JULY 
favorable. The nature of the results on Pinus ponderosa and P. 
contorta, although demonstrating that this mistletoe under very 
favorable conditions will infect yellow pines, does not show any great 
affinity for the genus. When it is recalled that goo seeds were sown 
on 18 individuals of Pinus ponderosa, each receiving 50 seeds, result- 
ing in one infection, and one infection on P. contorta out of 12 trees 
tested with 600 seeds, the relationship between these 2 tree species 
and the larch mistletoe cannot be very close. The same is appar- 
ently true with regard to the infection of Abies grandis. Six 
trees were tested with the usual number of seeds, but only 1 
infection resulted, which later died. These cultures also show 
that seeds germinating in the most vulnerable places only cause 
infection. Out of 500 seeds sown on Larix only 10 were able to 
cause infection, although apparently all the seeds which remained 
on the trees germinated. All were sown on parts of branches or 
shoots not over 6 years old, and care was taken to place the seeds 
favorably. It is to be expected that some of the seeds in outdoor 
cultures are removed by wind, rain, snow, insects, or birds. The 
observations relative to the favorableness of seed placement do not 
apply in the same way to the cultures on Pinus and Abies, since 
the larch mistletoe does not exhibit any marked affinity for these 
genera. That the same species of mistletoe growing on different 
hosts or under different conditions on the same host may exhibit 
different morphological characters is clearly demonstrated by 
these cultures. 
Since these experiments with the larch mistletoe were started, 
the following field observations have been made near Fernan Lake, 
Idaho. A large veteran western larch severely infected with 
R. laricis was left standing in a clearing which reseeded to Pinus 
ponderosa and P. contorta. From one each of these species growing 
directly under the larch typical, although small, specimens of the 
larch mistletoe bearing both pistillate and staminate plants were 
collected. The only true pine mistletoe in the immediate vicinity 
was R. americana. In a canyon near Missoula, Montana, where 
the larch is seriously infected with R. laricis and the pine mistletoes 
are not known to occur, specimens of the former have been collected 
from a single infection on Pinus contorta. These results are very 
