1900] von Schrenk,— Notes on Arceuthobium pusillum 3 
odd that the mistletoe should occur on an island at least five miles 
from the nearest mainland, and a vigorous search was made on the 
coast of the mainland for the plants. Hundreds of trees were found 
about Boothbay Harbor and Linekin, on which the mistletoe grew in 
quantities. The trees attacked varied from such as were but a few feet 
in height to the tallest in the forest, often eighty feet in height. The 
affected trees all grew within an eighth of a mile of the shore. ‘This 
local distribution is probably due to the fact that an atmosphere laden 
with moisture is necessary in order that the seeds may be properly 
discharged. The fogs which are so prevalent during the months of 
August and September bring about these conditions, which will be most 
favorable near the coast. 
As the accounts which have appeared up to this time give but 
short and scattering notes, a brief description of the plant may be of 
interest. In the unpublished notes of Dr. Engelmann, there are many 
drawings and descriptions, made at the time when the plant was dis- 
covered, which will be published, together with a fuller account of the 
plant and its western allies, in a more extended form. 
The mistletoe is usually found on the younger branches of the 
spruces.” Many stems grow out from the host branch, sometimes 
twelve to sixteen stems in an inch. The individual stems vary between 
wide extremes as respects size and color. Both characters depend so 
much on the vigor of the host branch that this variability is to be 
expected. On very strong branches the stems are dark brown, almost 
black, and vary from half an inch to an inch or more in height. Qn 
weaker branches the plants are paler in color, and usually have a more 
spindling shape. The vigor of the host plant is, however, not the only 
factor, exposure to the direct rays of the sun, the number of stems in a 
given length of the host stem, and probably other factors determine 
the character of each stem. One finds strong, dark-colored stems in 
the midst of a dense broom, and, again, very pale ones. 
The influence of the Arceuthobium on its host is probably the most 
marked feature of this interesting plant. In many cases where a 
parasite attacks a host-plant, the latter reacts in one way or another, as 
ifstimulated. Increased growth takes place, new tissues and organs 
are formed, which are in striking contrast to the normal habit of the 
host. Arceuthobium pusillum stimulates its host to a greater degree 
1 In the following, by spruce, P. Canadensis, B. S. P. (P. alba, Link), will be 
understood. 
