THE ORIGIN AND DEVELOPMENT OF THE GALLS PRO- 
DUCED BY TWO CEDAR RUST FUNGI 
J. L. Weimer 
The question of the origin of the outgrowths caused by Gymno- 
sporangium Jtmiperi-virginianae Schwein. and Gymno sporangium 
glohosum Farlow on Juniperus virginiana L. has never been settled 
satisfactorily. The galls produced by G. Juniperi-virginianae have 
been studied by several workers but there still exists considerable 
difference of opinion as to the method of their origin. The excres- 
cences caused by G. glohosum have been studied but little. 
While making observations on these galls incident to the prepara- 
tion of another paper the writer became interested in their method of 
origin. Observations were made throughout two summers and the 
earliest stages of the development of these galls were studied in the 
field and later microscopical studies were made. The results of these 
observations and studies together with a resume of the literature on 
the subject are given below. 
G. Juniperi-virginianae 
Farlow (1880) states that prior to the time of writing it had been 
generally accepted that the cedar apples originated in the young cedar 
stems but that so far as he could ascertain they were deformed leaves. 
Sanford (1888) studied the pathological histology of the galls produced 
by this fungus and decided that the galls are modified cedar leaves, 
while Wornle (1894) after also studying these galls histologically 
concluded that they originated from the stem. Heald (1909) thinks 
that the cedar apples originate from the stem in the axis of a leaf. 
Kern (1911) places G. Juniperi-virginianae among the foliage inhabit- 
ing species and Coons (191 2) states that while he has never observed 
or produced infection artificially it is evidently a leaf infection. Reed 
and Crabill (191 5) claim that the cedar apple is nothing but a hyper- 
trophy of a cedar leaf infected by the fungus G. Juniperi-virginianae. 
Giddings and Berg (1915) picture minute galls situated near the end 
of cedar leaves, hence apparently originating from the leaf. Steward 
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