30 
Journal of Mycology 
[Vol. 11 
IS AN AECIDIUM SUPPRESSED? 
An article appeared in the Botanical Gazette, 38:64-67, July 
1904, entitled The Aecidium of Maize Rust, by J. C. Arthur, in 
which it is shown experimentally that secidiospores from Oxalis 
cymosa Small placed on leaves of Maize plants produce uredo- 
spores. The following may be quoted from this author: “This 
prompt and very abundant appearance of the uredo could be inter¬ 
preted only as the result of the aecidial infection, for corn rust 
had not yet appeared out of doors, and even if it had, such 
an unusual attack following closely within the time limit of incu¬ 
bation would be highly improbable. It may therefore be consid¬ 
ered proved that the aecidium of Puccinia Sorghi Schw. occurs 
upon Oxalis, and a verification with teleutosporic material can 
be confidently undertaken in due time.” 
This result suggested that in spite of two successful inocu¬ 
lations with teleutospores of Maize Rust resulting in the produc¬ 
tion of uredospores (Expts. 261, 361), a mistake may have been 
made. Therefore a third infection experiment was undertaken 
July 15. Precaution was taken to grow and keep the host plants 
in a section of the greenhouse far removed from that portion in 
which the former experiments were carried on, to obviate so far 
as possible any accidental infection. The usual precautions were 
taken in making the inoculation — teleutospores from Sween Corn 
grown in the field the previous season being used. After nine days 
a pustule of uredospores put in an appearance — and thus for the 
third time during the period of my inoculation work extending 
from Jan. 16 to July 15, uredospores followed directly upon the 
application of teleutospores. 
If these experiments can be relied on, we may say that while 
Puccinia sorghi Pers. is a heteroecious species (as proven by Dr. 
Arthur’s experiment quoted above) it is able at times to suppress 
it's aecidial stage. We may say besides — judging from the 
prevalence of the uredo and teleuto stages and the rarity of the 
aecidium, supposing the work of the two experimenters has really 
furnished results as recorded — that in the great corn growing 
belt of our country the aecidial stage is usually suppressed, 
SUNFLOWER RUST — PUCCINIA HELIANTHI Schw. 
In spite of an abundance of experimental work with Puccinia 
helianthi Schw. there is not a unanimity of opinion in reference 
to this common Rust. Whether there are two valid species, P. 
helianthi Schw. and P. helianthorum Schw., or only one; or 
whether there are several ‘physiological species’; is not as yet 
agreed upon. Recent inoculation work leads me to think there is 
but one valid species and that there are no recognizable ‘biologic’ 
forms. 
I was kindly furnished good teleutosporic material by Pro¬ 
fessor F. L. Stevens, collected at Raleigh, North Carolina, on 
