LARCH MISTLETOE. 



THE LARCH MISTLETOE. 



This bulletin deals in the main with the immediate practical results 

 of an investigation of the injurious effects of the larch mistletoe on its 

 host in the Blue Mountain region of Oregon and serves to introduce 

 one of a series of studies on the mistletoes of coniferous trees in 

 general. The larch mistletoe (fig. 1). originally named Razoumof- 

 skya douglasii laricis by Piper 1 and given as a subspecies of the 

 Douglas-fir mistletoe, has recently been raised by the same writer 2 

 to the rank of a full species under the following name and description : 



Razownof.sk ya laricis Piper. Pistillate plants olivaceous, clustered, 5-8 cm. 

 long, branched; joints 1.5-2 mm. thick, sharply 4 angled; staminate swollen, 



yellow, the flowers in short spikes; lobes ovate, acute 

 bluish, 4 mm. long. Common on Lariat accident alia. 



The investig a t i o n 

 Avas begun in the Whit- 

 man National Forest, 

 Oreg. For some time 

 the general and grad- 

 ual deterioration of the 

 western larch had been 

 reported as occurring 

 throughout the entire 

 Blue Mountain region. 

 The writer was not 

 aware of the great 

 prevalence of the larch 

 mistletoe in this region 

 until his visit there 

 during the early 

 spring of 1913. From 

 a preliminary survey it 

 soon developed that 



fruit oblong, acutish, 



■INC 



"\\ V Id 1 



"\ \\l lilllk-> J 





■^--Oi ii ^S9E?i 



;a .r.m 



W 





Fig. 1.- 



-Staminate plants of Razoumofskya laricis. Note 

 the hypertrophy of the branch. 



the primary cause of the deterioration of the larch resulted from the 

 suppressing effects of mistletoe. A probable secondary factor on 

 some of the more exposed sites seemed to be certain climatic influences 

 unfavorable to the host but promoting the better development and 

 spread of the parasite. 



THE FOREST. 



The Blue Mountains, in which further studies of the mistletoes are 

 in progress, are well covered with forests. The yellow pine pre- 



1 Piper, C. V. Flora of the State of Washington. 17. S. Nat. Mus.. Contrib. Nat. 

 Herbarium, v. 11. p. 222. 1906. 



2 Piper, C. V., and Beattie, R. K. Flora of Southeastern Washington and Adjacent 

 Idaho, p. 80. Lancaster, Pa., 1914. 



