72 
Journal oj Agricultural Research 
Vol. XXX, No 1 
No basis was found for the idea that 
the rust is in any sense perennial or 
that any condition* approaching an 
“unlimited infection” is evident. It 
would appear that all of the structures 
develop from a localized mycelium and 
that this mycelium in all cases (except 
the late crop of telia) arises from basid- 
iospore infection. It is also evident 
that the first spore structure borne on 
this mycelium may be either telia, or 
pycnia accompanied by aecia, and in 
rare cases aecia without pycnia. 
These experiments when taken to¬ 
gether with field observations made at 
Ithaca, N. Y., and La Fayette, Ind., 
would seem to make necessary an inter¬ 
pretation entirely different from that 
made by Olive. 
LIFE HISTORY AND SEQUENCE OF 
SPORE FORMS 
It seems desirable, therefore, as a 
basis for further discussion, that the 
writers here set forth in some detail 
what they conceive to be the regular 
sequence of events in the life history 
of this rust. 
In the spring, at the time when the 
buds of the Podophyllum plant are 
emerging from the ground, the telio- 
spores of Puccinia podophylli are pres¬ 
ent in the surface layer of soil around 
the developing buds. These telio- 
spores are derived both from the spring 
crop of telia on leaf sheaths, stems, and 
sepals and those associated with aecial 
lesions, and from the summer crop pro¬ 
duced on the leaf blades. They have 
either fallen to the ground during the 
previous summer, as the telia are of the 
pulverulent type, the pedicles breaking 
close to the spore, or they have been 
liberated by the rather complete disin¬ 
tegration of the host tissues. The 
spore wall is beset with sparsely scat¬ 
tered rather long spines which would 
serve to prevent the spores from being 
carried too deeply into the soil or 
washed away during heavy rains. 
At the time when the sheathed leaf 
buds begin to push their pointed tips 
above the surface of the soil, these telio- 
spores (of both crops) begin to germi¬ 
nate in the normal w T ay for teliospores, 
that is, by the development of a typical 
promycelium and sporidia. The scale 
leaves form a sheath about the base of 
the stem, through which the young 
plant emerges. These scale leaves 
usually extend slightly above the 
ground level. The lobes of the two 
peltate leaves of the flowering stalk 
are folded about the stem in a convolute 
manner and the single blossom bud is 
partly exposed. 
The basidiospores fall upon the por¬ 
tions of the plant which are exposed 
in the early stage of development and 
infection results. The sheath leaves 
or bud scales are the first organs ex¬ 
posed. As the aerial stalk pushes forth 
from within the enfolding bud scales, 
both the base of the stem and the leaf 
blade are also exposed to infection. 
The upper part of the stem is rarely 
infected as it long remains protected 
by the enfolding leaf blades. The two 
sepals of the flower are, however, not 
uncommonly infected, for they are usu¬ 
ally partly exposed as the young plant 
emerges (PI. 1, A and B). 
The period of basidiospore produc¬ 
tion (that is, teliospore germination) 
apparently is relatively early and short. 
Very numerous infections occur on the 
scale leaves and on the base of the 
stems. This is perhaps due to the fact 
that they are nearer the soil surface 
and in the more effective zone of 
basidiospore dissemination. At Ithaca 
it has been noted in some seasons that 
only certain scale leaves, such, for ex¬ 
ample, as the second from the top, show 
infection. This observation (Whet- 
zel’s) was referred to by Olive as a 
“curious fact.” The explanation is, 
however, comparatively simple. These 
“second” scale leaves were the only 
ones exposed in the particular patch 
under observation at the time of in¬ 
oculation. There are three or more of 
these buds scales at the base of the 
stem. The top scale had not emerged 
from within the protecting outer second 
scale and the shorter third scale was 
still covered by leaf mold. It has 
since been observed, in the same patch, 
that all the scales and the base of the 
stem may be infected. It would appear 
that these differences are the result of 
seasonal variation in the coincidence 
of basidiospore production and de¬ 
velopment of the host and of variations 
in the extent of exposure of the bud 
scales above the surface of the leaf 
mold. 
From the basidiospore infections on 
the scale leaves, the base of the stem, 
and the sepals, telial sori are developed 
almost exclusively. Pycnia and aecia 
are occasionally found intermixed with 
the telia, the latter usually occurring 
singly. Both are, however, rather rare, 
and by far the greater number of 
lesions include telia only. In one case 
noted at LaFayette an isolated lesion 
on the stem bore a group of pycnia 
surrounded by a ring of telial sori, 
exactly similar in appearance to many 
true microforms of Puccinia. 
The occasional development of pyc¬ 
nia and aecia among the telia on sheath 
