OBSERVATIONS ON FOREST TREE RUSTS 
333 
disclose any stage of P. pustulatum upon E. adenocaulon other than 
the uredinial stage (N. A. U. Nos. 77 and 1087, Fungi Col. Nos. 2575, 
2782, 3180, 3773, and 4334, Fungi Dakotensis No. 371, and Jackson's 
Col. No. 1488). Many collections of the II stage have been made by 
the writers in months of the year which appear very much out of 
season for this stage of the rust as the following dates show: March 20, 
1916, April 12, 1916, May 4, 1916, June 3 and 15, 1916, July 9, and 
14, 1915, August 4 and 20, 1915, September 2, 10, and 28, 1916, 
October 11, 21, and 28, 1916, November 14, 1916. This indicates a 
continuation of the uredinial stage throughout the entire year. Ex- 
amination of all local and acquired collections fails to show where a 
single collection of the telial stage has been made. On October 18, 
1 9 16, three rosettes of Epilohium adenocaulo?i were secured in the field 
and potted in the greenhouse. Two of the rosettes bore the uredinial 
stage of Pucciniastrum pustulatum on such portions of the leaves as 
were protected by the outer rosette leaves. All the leaves of the 
infected rosettes were cut off, care being taken to remove all rusted 
areas and to cut back the leaves as close to their bases as possible. The 
only two sources of infection remaining open to the oncoming leaves 
were the very few urediniospores and the possible mycelium in the 
portions of the leaves left on the plants. New leaves gradually 
appeared and on November i several of them bore the uredinial stage 
of the rust. A large number of spores were liberated by these few 
infections. Germination tests of the spores showed a large percent 
germinating. A few days later spores were collected which had 
germinated in situ on the rosettes and produced a small mat of my- 
celium. Examination of the portions of leaves left on the rosettes 
after cutting off the infected leaves showed that considerable mycelium 
was present in the cells of the mesophyll just beneath the epidermis. 
From November 15 to 22 the rosettes developed a few leaves from two 
to two and one half inches from the ground, indicating a departure 
from the strictly rosette habit due to the temperature of the green- 
house. The lowermost ones developed uredinia in abundance. The 
uppermost leaves as yet showing no infection were sprinkled with 
urediniospores taken from the pustules beneath on November 18, 
1916. On November 27 uredinia developed on the leaves thus inocu- 
lated. Two control plants remained normal. The preceding data 
indicate the presence of a biological species of P. pustulatum occurring 
on E. adenocaulon and overwintering by means of mycelium and 
