The Dissemination and Germination of 
Arceuthobium occidentale, Eng . 1 
BY 
GEORGE J. PEIRCE. 
Associate Professor of Plant Physiology , Stanford University , California. 
With Plates III and IV. 
Introduction. 
‘ O O much has already been written on this genus of the Loranthaceae that 
O many will no doubt be surprised that there should be anything new 
to be said on the subject/ From this modest introduction Johnson (1888) 
proceeds to a description of Arceuthobium Oxycedri , which is the more 
remarkable for its excellence when one realizes the meagreness of the 
material at his disposal. If it were not that I have had the opportunity 
to study another species alive and out of doors, as well, as in the laboratory, 
to see it disseminating its ‘ seeds/ and to observe their germination, I should 
have no excuse for attempting to add anything to Johnson’s paper. As it 
is, I hope to be able to clear up certain matters which have hitherto been 
obscure. 
The material of Arceuthobium occidentale , Eng., which I have studied 
was on trees, young and old, of Pinus radiata , D. Don., the Monterey Pine 2 , 
which grows wild mainly along the shore of Monterey Bay on the coast 
of California. It is also abundantly planted about San Francisco Bay, 
and elsewhere. The affected trees which I studied were either in the 
Arboretum of Stanford University, where Arceuthobium has of late suffered 
greatly from the general improvement of the Arboretum, or in the forest 
on Point Pinos, one of the heads bounding Monterey Bay. This forest 
protects the town of Pacific Grove from the inward blowing sand which, 
instead of piling up as at present in fine dunes, would otherwise blow 
over and bury the town. The preservation of this forest is therefore 
important, a matter made very serious from the extraordinary number of 
untoward influences, natural and artificial, now operating there. A careful 
study of one of the enemies of this pine, therefore, may lead to practical 
advantages as well as to facts of some botanical interest. 
1 Read before the Botanical Section of the British Association, Cambridge, August, 1904. 
2 For a study of the effects of another parasite which attacks this pine see Peirce, G. J., Notes 
on the Monterey Pine, Botanical Gazette, vol. xxxvii, 1904. 
[Annals of Botany, Vol. XIX. No. LXXIII. January, 1905.] 
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