8 BOTANICAL GAZETTE [JULY 
the same regions where the yellow pine mistletoe occurs, has the 
same diseases attacking it, 
and is not found in regions 
where the typical R. tsugensis 
is most abundant and which 
it also slightly resembles, 
indicate that it may be a 
biological form of the former. 
The results of a number of 
cultures involving the three 
plants mentioned are pre- 
sented in table I. 
It will be seen from table 
I that an effort has been 
made to sow the seed of the 
large mistletoes on Pinus 
ponderosa (figs. 1-6) from 
several localities on as many 
—R. occidentalis abietina on Abies different hosts as possible 
Canesten: staminate and pistillate plants; 0 
Oregon. and on the same host in 
widely separate regions. 
The object of the latter was to try to determine the ae 
of the common mistletoes 
with thick, robust stems on 
yellow pine in the Rocky 
Mountain region to the more 
slender form on the same 
host in the Pacific Coast 
region. This problem has 
been sufficiently outlined 
previously. The cultures so 
far do not furnish any evi- 
dence that the two forms 
should be considered identi- 
cal. Plants in the Pacific 
Coast region resulting from seed collected in the northern Rocky 
Mountain region, and vice versa; exhibit various color varia- 
Fic. 8.—R. occidentalis abietina on Abies 
nobilis: staminate plants; Oregon. 
